Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-15 Thread Ihar Hrachyshka
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Hash: SHA512

On 12/09/14 19:08, Doug Hellmann wrote:
 
 On Sep 12, 2014, at 1:03 PM, Ihar Hrachyshka ihrac...@redhat.com
 wrote:
 
 Signed PGP part On 12/09/14 17:30, Mike Bayer wrote:
 
 On Sep 12, 2014, at 10:40 AM, Ihar Hrachyshka
 ihrac...@redhat.com wrote:
 
 Signed PGP part On 12/09/14 16:33, Mike Bayer wrote:
 I agree with this, changing the MySQL driver now is not an 
 option.
 
 That was not the proposal. The proposal was to introduce
 support to run against something different from MySQLdb + a
 gate job for that alternative. The next cycle was supposed to
 do thorough regression testing, benchmarking, etc. to decide
 whether we're ok to recommend that alternative to users.
 
 ah, well that is a great idea.  But we can have that
 throughout Kilo anyway, why not ?
 
 Sure, it's not the end of the world. We'll just need to postpone
 work till RC1 (=opening of master for new stuff), pass spec
 bureauracy (reapplying for kilo)... That's some burden, but not
 tragedy.
 
 The only thing that I'm really sad about is that Juno users won't
 be able to try out that driver on their setup just to see how it
 works, so it narrows testing base to gate while we could get some
 valuable deployment feedback in Juno already.
 
 It’s all experimental, right? And implemented in libraries? So
 those users could update oslo.db and sqlalchemy-migrate and test
 the results under Juno.

oslo.db is already bumped to the version that includes all those fixes
needed. As for sqlalchemy-migrate, we may try to work on a fix for the
library that will silently drop those COMMIT statements in SQL
scripts. That would solve the problem without touching any migration
code in nova, glance, or cinder. This is the piece that is currently
missing to run Juno with that alternative driver. Also, as Angus said,
we already can run migrations on mysqldb and then switch it for
testing, without any of the changes.

I'll work on making sure it's available to check out with Juno pieces
in addition to Kilo.

/Ihar
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-15 Thread Ihar Hrachyshka
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On 12/09/14 18:00, Mike Bayer wrote:
 
 On Sep 12, 2014, at 11:56 AM, Johannes Erdfelt
 johan...@erdfelt.com wrote:
 
 On Fri, Sep 12, 2014, Doug Hellmann d...@doughellmann.com
 wrote:
 I don’t think we will want to retroactively change the
 migration scripts (that’s not something we generally like to
 do),
 
 We don't allow semantic changes to migration scripts since people
 who have already run it won't get those changes. However, we
 haven't been shy about fixing bugs that prevent the migration
 script from running (which this change would probably fall
 into).
 
 fortunately BEGIN/ COMMIT are not semantic directives. The
 migrations semantically indicated by the script are unaffected in
 any way by these run-environment settings.
 
 
 
 so we should look at changes needed to make sqlalchemy-migrate
 deal with them (by ignoring them, or working around the errors,
 or whatever).
 
 That said, I agree that sqlalchemy-migrate shouldn't be changing
 in a non-backwards compatible way.
 
 on the sqlalchemy-migrate side, the handling of it’s ill-conceived
 “sql script” feature can be further mitigated here by parsing for
 the “COMMIT” line when it breaks out the SQL and ignoring it, I’d
 favor that it emits a warning also.

I went on with ignoring COMMIT specifically in SQL scripts:
https://review.openstack.org/#/c/121517/ Though we could also ignore
other transaction managing statements in those scripts, like ROLLBACK,
they are highly unlikely to occur in migration code, so I ignore them
in the patch.

/Ihar
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Ihar Hrachyshka
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Some updates/concerns/questions.

The status of introducing a new driver to gate is:

- - all the patches for mysql-connector are merged in all projects;
- - all devstack patches to support switching the driver are merged;
- - new sqlalchemy-migrate library is released;

- - version bump is *not* yet done;
- - package is still *not* yet published on pypi;
- - new gate job is *not* yet introduced.

The new sqlalchemy-migrate release introduced unit test failures in
those three projects: nova, cinder, glance.

On technical side of the failure: my understanding is that those
projects that started to fail assume too much about how those SQL
scripts are executed. They assume they are executed in one go, they
also assume they need to open and commit transaction on their own. I
don't think this is something to be fixed in sqlalchemy-migrate
itself. Instead, simple removal of those 'BEGIN TRANSACTION; ...
COMMIT;' statements should just work and looks like a sane thing to do
anyway. I've proposed the following patches for all three projects to
handle it [1].

That said, those failures were solved by pinning the version of the
library in openstack/requirements and those projects. This is in major
contrast to how we handled the new testtools release just several
weeks ago, when the problem was solved by fixing three affected
projects because of their incorrect usage of tearDown/setUp methods.

Even more so, those failures seem to trigger the resolution to move
the enable-mysql-connector oslo spec to Kilo, while the library
version bump is the *only* change missing codewise (we will also need
a gate job description, but that doesn't touch codebase at all). The
resolution looks too prompt and ungrounded to me. Is it really that
gate failure for three projects that resulted in it, or there are some
other hidden reasons behind it? Was it discussed anywhere? If so, I
wasn't given a chance to participate in that discussion; I suspect
another supporter of the spec (Agnus Lees) was not involved either.

Not allowing those last pieces of the spec in this cycle, we just
postpone start of any realistic testing of the feature for another
half a year.

Why do we block new sqlalchemy-migrate and the spec for another cycle
instead of fixing the affected projects with *primitive* patches like
we did for new testtools?

[1]:
https://review.openstack.org/#/q/I10c58b3af75d3ab9153a8bbd2a539bf1577de328,n,z

/Ihar

On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing other
 threads to eventually unlock the grabbed lock, and instead it just
 blocks the main thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving failing request not 
 served. In Nova, there is a special retry mechanism for deadlocks, 
 though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not something
 to change in foreseeable future, so we need to find another
 solution that is applicable for Juno. Ideally, the solution should
 be applicable for Icehouse too to allow distributors to resolve
 existing deadlocks without waiting for Juno.
 
 We've had several discussions and attempts to introduce a solution
 to the problem. Thanks to oslo.db guys, we now have more or less
 clear view on the cause of the failures and how to easily fix them.
 The solution is to switch mysqldb to something eventlet aware. The
 best candidate is probably MySQL Connector module that is an
 official MySQL client for Python and that shows some (preliminary)
 good results in terms of performance.
 
 I've posted a Neutron spec for the switch to the new client in Juno
 at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer to
 the new official way to configure services for MySQL. The database
 code won't, ideally, require any major changes, though some
 adaptation for the new client library may be needed. That said,
 Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone or
 Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious wish
 to switch to the new library globally 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Sean Dague
On 09/12/2014 06:41 AM, Ihar Hrachyshka wrote:
 Some updates/concerns/questions.
 
 The status of introducing a new driver to gate is:
 
 - all the patches for mysql-connector are merged in all projects;
 - all devstack patches to support switching the driver are merged;
 - new sqlalchemy-migrate library is released;
 
 - version bump is *not* yet done;
 - package is still *not* yet published on pypi;
 - new gate job is *not* yet introduced.
 
 The new sqlalchemy-migrate release introduced unit test failures in
 those three projects: nova, cinder, glance.
 
 On technical side of the failure: my understanding is that those
 projects that started to fail assume too much about how those SQL
 scripts are executed. They assume they are executed in one go, they
 also assume they need to open and commit transaction on their own. I
 don't think this is something to be fixed in sqlalchemy-migrate
 itself. Instead, simple removal of those 'BEGIN TRANSACTION; ...
 COMMIT;' statements should just work and looks like a sane thing to do
 anyway. I've proposed the following patches for all three projects to
 handle it [1].
 
 That said, those failures were solved by pinning the version of the
 library in openstack/requirements and those projects. This is in major
 contrast to how we handled the new testtools release just several
 weeks ago, when the problem was solved by fixing three affected
 projects because of their incorrect usage of tearDown/setUp methods.
 
 Even more so, those failures seem to trigger the resolution to move
 the enable-mysql-connector oslo spec to Kilo, while the library
 version bump is the *only* change missing codewise (we will also need
 a gate job description, but that doesn't touch codebase at all). The
 resolution looks too prompt and ungrounded to me. Is it really that
 gate failure for three projects that resulted in it, or there are some
 other hidden reasons behind it? Was it discussed anywhere? If so, I
 wasn't given a chance to participate in that discussion; I suspect
 another supporter of the spec (Agnus Lees) was not involved either.
 
 Not allowing those last pieces of the spec in this cycle, we just
 postpone start of any realistic testing of the feature for another
 half a year.
 
 Why do we block new sqlalchemy-migrate and the spec for another cycle
 instead of fixing the affected projects with *primitive* patches like
 we did for new testtools?

Because we are in Feature Freeze. Now is the time for critical bug fixes
only, as we start to stabalize the tree. Releasing dependent libraries
that can cause breaks, for whatever reason, should be soundly avoided.

If this was August, fine. But it's feature freeze.

-Sean

-- 
Sean Dague
http://dague.net



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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Ihar Hrachyshka
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Hash: SHA512

On 12/09/14 13:20, Sean Dague wrote:
 On 09/12/2014 06:41 AM, Ihar Hrachyshka wrote:
 Some updates/concerns/questions.
 
 The status of introducing a new driver to gate is:
 
 - all the patches for mysql-connector are merged in all
 projects; - all devstack patches to support switching the driver
 are merged; - new sqlalchemy-migrate library is released;
 
 - version bump is *not* yet done; - package is still *not* yet
 published on pypi; - new gate job is *not* yet introduced.
 
 The new sqlalchemy-migrate release introduced unit test failures
 in those three projects: nova, cinder, glance.
 
 On technical side of the failure: my understanding is that those 
 projects that started to fail assume too much about how those
 SQL scripts are executed. They assume they are executed in one
 go, they also assume they need to open and commit transaction on
 their own. I don't think this is something to be fixed in
 sqlalchemy-migrate itself. Instead, simple removal of those
 'BEGIN TRANSACTION; ... COMMIT;' statements should just work and
 looks like a sane thing to do anyway. I've proposed the following
 patches for all three projects to handle it [1].
 
 That said, those failures were solved by pinning the version of
 the library in openstack/requirements and those projects. This is
 in major contrast to how we handled the new testtools release
 just several weeks ago, when the problem was solved by fixing
 three affected projects because of their incorrect usage of
 tearDown/setUp methods.
 
 Even more so, those failures seem to trigger the resolution to
 move the enable-mysql-connector oslo spec to Kilo, while the
 library version bump is the *only* change missing codewise (we
 will also need a gate job description, but that doesn't touch
 codebase at all). The resolution looks too prompt and ungrounded
 to me. Is it really that gate failure for three projects that
 resulted in it, or there are some other hidden reasons behind it?
 Was it discussed anywhere? If so, I wasn't given a chance to
 participate in that discussion; I suspect another supporter of
 the spec (Agnus Lees) was not involved either.
 
 Not allowing those last pieces of the spec in this cycle, we
 just postpone start of any realistic testing of the feature for
 another half a year.
 
 Why do we block new sqlalchemy-migrate and the spec for another
 cycle instead of fixing the affected projects with *primitive*
 patches like we did for new testtools?
 
 Because we are in Feature Freeze. Now is the time for critical bug
 fixes only, as we start to stabalize the tree. Releasing dependent
 libraries that can cause breaks, for whatever reason, should be
 soundly avoided.
 
 If this was August, fine. But it's feature freeze.

I probably missed the fact that we are so strict now that we don't
allow tiny missing bits to go in. In my excuse, I was offline for
around three last weeks. I was a bit misled by the fact that I was
approached by an oslo core very recently on which remaining bits we
need to push before claiming the spec to be complete, and I assumed it
means that we are free to complete the work this cycle. Otherwise, I
wouldn't push for the new library version in the first place.

Anyway, I guess there is no way now to get remaining bits in Juno,
even if small, and we're doomed to postpone them to Kilo.

Thanks for the explanation,
/Ihar
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Jeremy Stanley
On 2014-09-12 12:41:42 +0200 (+0200), Ihar Hrachyshka wrote:
[...]
 That said, those failures were solved by pinning the version of the
 library in openstack/requirements and those projects. This is in major
 contrast to how we handled the new testtools release just several
 weeks ago, when the problem was solved by fixing three affected
 projects because of their incorrect usage of tearDown/setUp methods.
[...]

This was of course different because it came during a period where
integrated projects are supposed to be focusing on stabilizing what
they have toward release, but also our behavior was somewhat altered
because we needed to perform some immediate damage control.

One of the side-effects of the failure mode this sqlalchemy-migrate
release induced was that each nova unit tests was generating ~0.5GiB
of log data, instantly overwhelming our test log analysis systems
and flooding our artifact archive (both in terms of bandwidth and
disk). The fastest way to stop this was to roll back what changed,
for which the options were either to introduce an exclusionary
version pin or convince the library authors to release an even newer
version tagged to the old one. We chose the first solution as it was
more directly under the control of the infrastructure and nova core
teams involved at that moment.
-- 
Jeremy Stanley

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Mike Bayer

On Sep 12, 2014, at 7:20 AM, Sean Dague s...@dague.net wrote:

 
 Because we are in Feature Freeze. Now is the time for critical bug fixes
 only, as we start to stabalize the tree. Releasing dependent libraries
 that can cause breaks, for whatever reason, should be soundly avoided.
 
 If this was August, fine. But it's feature freeze.

I agree with this, changing the MySQL driver now is not an option.That 
train has left the station, I think it’s better we all take the whole Kilo 
cycle to get used to mysql-connector and its quirks before launching it on the 
world, as there will be many more.

However for Kilo, I think those “COMMIT” phrases should be removed and overall 
we need to make a very hard and fast rule that we *do not put multiple 
statements in an execute*.I’ve seen a bunch of these come through so far, 
and for some of them (more the in-Python ones) it seems like the underlying 
reason is a lack of understanding of what exactly a SQLAlchemy “Engine” is and 
what features it supports.

So first, let me point folks to the documentation for this, which anyone 
writing code involving Engine objects should read first:

http://docs.sqlalchemy.org/en/rel_0_9/core/connections.html

Key to this is that while engine supports an “.execute()” method, in order to 
do anything that intends to work on a single connection and typically a single 
transaction, you procure a Connection and usually a Transaction from the 
Engine, most easily like this:

with engine.begin() as conn:
   conn.execute(statement 1)
   conn.execute(statement 2)
   conn.execute(statement 3)
   .. etc


Now let me apologize for the reason this misunderstanding exists in the first 
place:  it’s because in 2005 I put the “.execute()” convenience method on the 
Engine itself (well in fact we didn’t have the Engine/Connection dichotomy back 
then), and I also thought that “implicit execution”, e.g. statement.execute(), 
would be a great idea.Tons of other people still think it’s a great idea 
and even though I’ve buried this whole thing in the docs, they still use it 
like candy….until they have the need to control the scope of connectivity.  

*Huge* mistake, it’s my fault, but not something that can really be changed 
now.   Also, in 2005, Python didn’t have context managers.So we have all 
kinds of klunky patterns like “trans = conn.begin()”, kind of J2EE style, etc., 
but these days, the above pattern is your best bet when you want to invoke 
multiple statements.engine.execute() overall should just be avoided as it 
only leads to misunderstanding.   When we all move all of our migrate stuff to 
Alembic, there won’t be an Engine provided to a migration script, it will be a 
Connection to start with.




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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 12/09/14 16:33, Mike Bayer wrote:
 I agree with this, changing the MySQL driver now is not an option.

That was not the proposal. The proposal was to introduce support to
run against something different from MySQLdb + a gate job for that
alternative. The next cycle was supposed to do thorough regression
testing, benchmarking, etc. to decide whether we're ok to recommend
that alternative to users.

/Ihar
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Doug Hellmann

On Sep 12, 2014, at 9:23 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:

 Signed PGP part
 On 12/09/14 13:20, Sean Dague wrote:
  On 09/12/2014 06:41 AM, Ihar Hrachyshka wrote:
  Some updates/concerns/questions.
 
  The status of introducing a new driver to gate is:
 
  - all the patches for mysql-connector are merged in all
  projects; - all devstack patches to support switching the driver
  are merged; - new sqlalchemy-migrate library is released;
 
  - version bump is *not* yet done; - package is still *not* yet
  published on pypi; - new gate job is *not* yet introduced.
 
  The new sqlalchemy-migrate release introduced unit test failures
  in those three projects: nova, cinder, glance.
 
  On technical side of the failure: my understanding is that those
  projects that started to fail assume too much about how those
  SQL scripts are executed. They assume they are executed in one
  go, they also assume they need to open and commit transaction on
  their own. I don't think this is something to be fixed in
  sqlalchemy-migrate itself. Instead, simple removal of those
  'BEGIN TRANSACTION; ... COMMIT;' statements should just work and
  looks like a sane thing to do anyway. I've proposed the following
  patches for all three projects to handle it [1].
 
  That said, those failures were solved by pinning the version of
  the library in openstack/requirements and those projects. This is
  in major contrast to how we handled the new testtools release
  just several weeks ago, when the problem was solved by fixing
  three affected projects because of their incorrect usage of
  tearDown/setUp methods.
 
  Even more so, those failures seem to trigger the resolution to
  move the enable-mysql-connector oslo spec to Kilo, while the
  library version bump is the *only* change missing codewise (we
  will also need a gate job description, but that doesn't touch
  codebase at all). The resolution looks too prompt and ungrounded
  to me. Is it really that gate failure for three projects that
  resulted in it, or there are some other hidden reasons behind it?
  Was it discussed anywhere? If so, I wasn't given a chance to
  participate in that discussion; I suspect another supporter of
  the spec (Agnus Lees) was not involved either.
 
  Not allowing those last pieces of the spec in this cycle, we
  just postpone start of any realistic testing of the feature for
  another half a year.
 
  Why do we block new sqlalchemy-migrate and the spec for another
  cycle instead of fixing the affected projects with *primitive*
  patches like we did for new testtools?
 
  Because we are in Feature Freeze. Now is the time for critical bug
  fixes only, as we start to stabalize the tree. Releasing dependent
  libraries that can cause breaks, for whatever reason, should be
  soundly avoided.
 
  If this was August, fine. But it's feature freeze.
 
 I probably missed the fact that we are so strict now that we don't
 allow tiny missing bits to go in. In my excuse, I was offline for
 around three last weeks. I was a bit misled by the fact that I was
 approached by an oslo core very recently on which remaining bits we
 need to push before claiming the spec to be complete, and I assumed it
 means that we are free to complete the work this cycle. Otherwise, I
 wouldn't push for the new library version in the first place.

I suspect you’re referring to me, there. I believed the work was ready to be 
wrapped up. I’m sorry my misunderstanding led to the issues.

 
 Anyway, I guess there is no way now to get remaining bits in Juno,
 even if small, and we're doomed to postpone them to Kilo.

I think we’re only looking at a couple of weeks delay. During that time we can 
work on fixing the problem. I don’t think we will want to retroactively change 
the migration scripts (that’s not something we generally like to do), so we 
should look at changes needed to make sqlalchemy-migrate deal with them (by 
ignoring them, or working around the errors, or whatever).

Doug

 
 Thanks for the explanation,
 /Ihar
 
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Sean Dague
On 09/12/2014 11:19 AM, Doug Hellmann wrote:
 
 On Sep 12, 2014, at 9:23 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:
 
 Signed PGP part
 On 12/09/14 13:20, Sean Dague wrote:
 On 09/12/2014 06:41 AM, Ihar Hrachyshka wrote:
 Some updates/concerns/questions.

 The status of introducing a new driver to gate is:

 - all the patches for mysql-connector are merged in all
 projects; - all devstack patches to support switching the driver
 are merged; - new sqlalchemy-migrate library is released;

 - version bump is *not* yet done; - package is still *not* yet
 published on pypi; - new gate job is *not* yet introduced.

 The new sqlalchemy-migrate release introduced unit test failures
 in those three projects: nova, cinder, glance.

 On technical side of the failure: my understanding is that those
 projects that started to fail assume too much about how those
 SQL scripts are executed. They assume they are executed in one
 go, they also assume they need to open and commit transaction on
 their own. I don't think this is something to be fixed in
 sqlalchemy-migrate itself. Instead, simple removal of those
 'BEGIN TRANSACTION; ... COMMIT;' statements should just work and
 looks like a sane thing to do anyway. I've proposed the following
 patches for all three projects to handle it [1].

 That said, those failures were solved by pinning the version of
 the library in openstack/requirements and those projects. This is
 in major contrast to how we handled the new testtools release
 just several weeks ago, when the problem was solved by fixing
 three affected projects because of their incorrect usage of
 tearDown/setUp methods.

 Even more so, those failures seem to trigger the resolution to
 move the enable-mysql-connector oslo spec to Kilo, while the
 library version bump is the *only* change missing codewise (we
 will also need a gate job description, but that doesn't touch
 codebase at all). The resolution looks too prompt and ungrounded
 to me. Is it really that gate failure for three projects that
 resulted in it, or there are some other hidden reasons behind it?
 Was it discussed anywhere? If so, I wasn't given a chance to
 participate in that discussion; I suspect another supporter of
 the spec (Agnus Lees) was not involved either.

 Not allowing those last pieces of the spec in this cycle, we
 just postpone start of any realistic testing of the feature for
 another half a year.

 Why do we block new sqlalchemy-migrate and the spec for another
 cycle instead of fixing the affected projects with *primitive*
 patches like we did for new testtools?

 Because we are in Feature Freeze. Now is the time for critical bug
 fixes only, as we start to stabalize the tree. Releasing dependent
 libraries that can cause breaks, for whatever reason, should be
 soundly avoided.

 If this was August, fine. But it's feature freeze.

 I probably missed the fact that we are so strict now that we don't
 allow tiny missing bits to go in. In my excuse, I was offline for
 around three last weeks. I was a bit misled by the fact that I was
 approached by an oslo core very recently on which remaining bits we
 need to push before claiming the spec to be complete, and I assumed it
 means that we are free to complete the work this cycle. Otherwise, I
 wouldn't push for the new library version in the first place.
 
 I suspect you’re referring to me, there. I believed the work was ready to be 
 wrapped up. I’m sorry my misunderstanding led to the issues.
 

 Anyway, I guess there is no way now to get remaining bits in Juno,
 even if small, and we're doomed to postpone them to Kilo.
 
 I think we’re only looking at a couple of weeks delay. During that time we 
 can work on fixing the problem. I don’t think we will want to retroactively 
 change the migration scripts (that’s not something we generally like to do), 
 so we should look at changes needed to make sqlalchemy-migrate deal with them 
 (by ignoring them, or working around the errors, or whatever).

Yes, please, that would be highly appreciated. That kind of backwards
compat guaruntees is kind of why we took over migrate in the first place
as a project.

-Sean

-- 
Sean Dague
http://dague.net

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Mike Bayer

On Sep 12, 2014, at 10:40 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:

 Signed PGP part
 On 12/09/14 16:33, Mike Bayer wrote:
 I agree with this, changing the MySQL driver now is not an option.
 
 That was not the proposal. The proposal was to introduce support to
 run against something different from MySQLdb + a gate job for that
 alternative. The next cycle was supposed to do thorough regression
 testing, benchmarking, etc. to decide whether we're ok to recommend
 that alternative to users.

ah, well that is a great idea.  But we can have that throughout Kilo anyway, 
why not ?





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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Johannes Erdfelt
On Fri, Sep 12, 2014, Doug Hellmann d...@doughellmann.com wrote:
 I don’t think we will want to retroactively change the migration scripts
 (that’s not something we generally like to do),

We don't allow semantic changes to migration scripts since people who
have already run it won't get those changes. However, we haven't been
shy about fixing bugs that prevent the migration script from running
(which this change would probably fall into).

 so we should look at changes needed to make sqlalchemy-migrate deal with
 them (by ignoring them, or working around the errors, or whatever).

That said, I agree that sqlalchemy-migrate shouldn't be changing in a
non-backwards compatible way.

JE


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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Mike Bayer

On Sep 12, 2014, at 11:56 AM, Johannes Erdfelt johan...@erdfelt.com wrote:

 On Fri, Sep 12, 2014, Doug Hellmann d...@doughellmann.com wrote:
 I don’t think we will want to retroactively change the migration scripts
 (that’s not something we generally like to do),
 
 We don't allow semantic changes to migration scripts since people who
 have already run it won't get those changes. However, we haven't been
 shy about fixing bugs that prevent the migration script from running
 (which this change would probably fall into).

fortunately BEGIN/ COMMIT are not semantic directives. The migrations 
semantically indicated by the script are unaffected in any way by these 
run-environment settings.


 
 so we should look at changes needed to make sqlalchemy-migrate deal with
 them (by ignoring them, or working around the errors, or whatever).
 
 That said, I agree that sqlalchemy-migrate shouldn't be changing in a
 non-backwards compatible way.

on the sqlalchemy-migrate side, the handling of it’s ill-conceived “sql script” 
feature can be further mitigated here by parsing for the “COMMIT” line when it 
breaks out the SQL and ignoring it, I’d favor that it emits a warning also.
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 12/09/14 17:30, Mike Bayer wrote:
 
 On Sep 12, 2014, at 10:40 AM, Ihar Hrachyshka ihrac...@redhat.com
 wrote:
 
 Signed PGP part On 12/09/14 16:33, Mike Bayer wrote:
 I agree with this, changing the MySQL driver now is not an
 option.
 
 That was not the proposal. The proposal was to introduce support
 to run against something different from MySQLdb + a gate job for
 that alternative. The next cycle was supposed to do thorough
 regression testing, benchmarking, etc. to decide whether we're ok
 to recommend that alternative to users.
 
 ah, well that is a great idea.  But we can have that throughout
 Kilo anyway, why not ?

Sure, it's not the end of the world. We'll just need to postpone work
till RC1 (=opening of master for new stuff), pass spec bureauracy
(reapplying for kilo)... That's some burden, but not tragedy.

The only thing that I'm really sad about is that Juno users won't be
able to try out that driver on their setup just to see how it works,
so it narrows testing base to gate while we could get some valuable
deployment feedback in Juno already.

 
 
 
 
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Doug Hellmann

On Sep 12, 2014, at 1:03 PM, Ihar Hrachyshka ihrac...@redhat.com wrote:

 Signed PGP part
 On 12/09/14 17:30, Mike Bayer wrote:
 
  On Sep 12, 2014, at 10:40 AM, Ihar Hrachyshka ihrac...@redhat.com
  wrote:
 
  Signed PGP part On 12/09/14 16:33, Mike Bayer wrote:
  I agree with this, changing the MySQL driver now is not an
  option.
 
  That was not the proposal. The proposal was to introduce support
  to run against something different from MySQLdb + a gate job for
  that alternative. The next cycle was supposed to do thorough
  regression testing, benchmarking, etc. to decide whether we're ok
  to recommend that alternative to users.
 
  ah, well that is a great idea.  But we can have that throughout
  Kilo anyway, why not ?
 
 Sure, it's not the end of the world. We'll just need to postpone work
 till RC1 (=opening of master for new stuff), pass spec bureauracy
 (reapplying for kilo)... That's some burden, but not tragedy.
 
 The only thing that I'm really sad about is that Juno users won't be
 able to try out that driver on their setup just to see how it works,
 so it narrows testing base to gate while we could get some valuable
 deployment feedback in Juno already.

It’s all experimental, right? And implemented in libraries? So those users 
could update oslo.db and sqlalchemy-migrate and test the results under Juno.

Doug


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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-09-12 Thread Angus Lees
On Fri, 12 Sep 2014 01:08:04 PM Doug Hellmann wrote:
 On Sep 12, 2014, at 1:03 PM, Ihar Hrachyshka ihrac...@redhat.com wrote:
  Signed PGP part
  
  On 12/09/14 17:30, Mike Bayer wrote:
   On Sep 12, 2014, at 10:40 AM, Ihar Hrachyshka ihrac...@redhat.com
   
   wrote:
   Signed PGP part On 12/09/14 16:33, Mike Bayer wrote:
   I agree with this, changing the MySQL driver now is not an
   option.
   
   That was not the proposal. The proposal was to introduce support
   to run against something different from MySQLdb + a gate job for
   that alternative. The next cycle was supposed to do thorough
   regression testing, benchmarking, etc. to decide whether we're ok
   to recommend that alternative to users.
   
   ah, well that is a great idea.  But we can have that throughout
   Kilo anyway, why not ?
  
  Sure, it's not the end of the world. We'll just need to postpone work
  till RC1 (=opening of master for new stuff), pass spec bureauracy
  (reapplying for kilo)... That's some burden, but not tragedy.
  
  The only thing that I'm really sad about is that Juno users won't be
  able to try out that driver on their setup just to see how it works,
  so it narrows testing base to gate while we could get some valuable
  deployment feedback in Juno already.
 
 It’s all experimental, right? And implemented in libraries? So those users
 could update oslo.db and sqlalchemy-migrate and test the results under
 Juno.

Note that it's also theoretically possible to run the migrate with mysqldb and 
the regular production service (post-migrate) with an alternate mysql driver 
that won't deadlock eventlet...  (ie: there's no reason the mysql driver 
choice needs to be universal and simultaneous)


I'm sad that we (as a project) still haven't been able to make this 
technically trivial fix - or even make it an option for testing - after the 
original problem was identified and the fix proposed 2.5+ months ago.  I'm 
encouraged to see various meta-threads popping up discussing issues with our 
development model and hopefully we can do better in future :(

-- 
 - Gus

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-21 Thread Angus Lees
On Wed, 20 Aug 2014 05:03:51 PM Clark Boylan wrote:
 On Mon, Aug 18, 2014, at 01:59 AM, Ihar Hrachyshka wrote:
  -BEGIN PGP SIGNED MESSAGE-
  Hash: SHA512
  
  On 17/08/14 02:09, Angus Lees wrote:
   On 16 Aug 2014 06:09, Doug Hellmann d...@doughellmann.com
   
   mailto:d...@doughellmann.com wrote:
   On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka
   ihrac...@redhat.com
   
   mailto:ihrac...@redhat.com wrote:
   Signed PGP part Some updates on the matter:
   
   - oslo-spec was approved with narrowed scope which is now
   'enabled mysqlconnector as an alternative in gate' instead of
   'switch the default db driver to mysqlconnector'. We'll revisit
   the switch part the next cycle once we have the new driver
   running in gate and real benchmarking is heavy-lifted.
   
   - there are several patches that are needed to make devstack
   and tempest passing deployment and testing. Those are collected
   under the hood of: https://review.openstack.org/#/c/114207/ Not
   much of them.
   
   - we'll need a new oslo.db release to bump versions (this is
   needed to set raise_on_warnings=False for the new driver, which
   was incorrectly set to True in sqlalchemy till very recently).
   This is expected to be released this month (as per Roman
   Podoliaka).
   
   This release is currently blocked on landing some changes in
   projects
   
   using the library so they don?t break when the new version starts
   using different exception classes. We?re tracking that work in
   https://etherpad.openstack.org/p/sqla_exceptions_caught
   
   It looks like we?re down to 2 patches, one for cinder
   
   (https://review.openstack.org/#/c/111760/) and one for glance
   (https://review.openstack.org/#/c/109655). Roman, can you verify
   that those are the only two projects that need changes for the
   exception issue?
   
   - once the corresponding patch for sqlalchemy-migrate is
   merged, we'll also need a new version released for this.
   
   So we're going for a new version of sqlalchemy?  (We have a
   separate workaround for raise_on_warnings that doesn't require the
   new sqlalchemy release if this brings too many other issues)
  
  Wrong. We're going for a new version of *sqlalchemy-migrate*. Which is
  the code that we inherited from Mike and currently track in stackforge.
  
   - on PyPI side, no news for now. The last time I've heard from
   Geert (the maintainer of MySQL Connector for Python), he was
   working on this. I suspect there are some legal considerations
   running inside Oracle. I'll update once I know more about
   that.
   
   If we don?t have the new package on PyPI, how do we plan to
   include it
   
   in the gate? Are there options to allow an exception, or to make
   the mirroring software download it anyway?
   
   We can test via devstack without waiting for pypi, since devstack
   will install via rpms/debs.
  
  I expect that it will be settled. I have no indication that the issue
  is unsolvable, it will just take a bit more time than we're accustomed
  to. :)
  
  At the moment, we install MySQLdb from distro packages for devstack.
  Same applies to new driver. It will be still great to see the package
  published on PyPI so that we can track its version requirements
  instead of relying on distros to package it properly. But I don't see
  it as a blocker.
  
  Also, we will probably be able to run with other drivers supported by
  SQLAlchemy once all the work is done.
 
 So I got bored last night and decided to take a stab at making PyMySQL
 work since I was a proponent of it earlier. Thankfully it did just
 mostly work like I thought it would.
 https://review.openstack.org/#/c/115495/ is the WIP devstack change to
 test this out.

Thanks!

 Postgres tests fail because it was applying the pymysql driver to the
 postgres connection string. We can clean this up later in devstack
 and/or devstack-gate depending on how we need to apply this stuff.
 Bashate failed because I had to monkeypatch in a fix for a ceilometer
 issue loading sqlalchemy drivers. The tempest neutron full job fails on
 one test occasionally. Not sure yet if that is normal neutron full
 failure mode or if a new thing from PyMySQL. The regular tempest job
 passes just fine.
 
 There are also some DB related errors in the logs that will need to be
 cleaned up but overall it just works. So I would like to repropose that
 we stop focusing all of this effort on the hard thing and use the easy
 thing if it meets our needs. We can continue to make alternatives work,
 but that is a different problem that we can solve at a different pace. I
 am not sure how to test the neutron thing that Gus was running into
 though so we should also check that really quickly.

TL;DR: pymysql passes my test case.
I'm perfectly happy to move towards using mysql+pymysql in gate tests.  (The 
various changes I've been submitting are to support _any_ non-default driver).

If anyone cares, my test case is in 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-21 Thread Endre Karlson
Why pymysql over mysql-python?

Endre Karlson
21. Aug. 2014 09:05 skrev Angus Lees g...@inodes.org følgende:

 On Wed, 20 Aug 2014 05:03:51 PM Clark Boylan wrote:
  On Mon, Aug 18, 2014, at 01:59 AM, Ihar Hrachyshka wrote:
   -BEGIN PGP SIGNED MESSAGE-
   Hash: SHA512
  
   On 17/08/14 02:09, Angus Lees wrote:
On 16 Aug 2014 06:09, Doug Hellmann d...@doughellmann.com
   
mailto:d...@doughellmann.com wrote:
On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka
ihrac...@redhat.com
   
mailto:ihrac...@redhat.com wrote:
Signed PGP part Some updates on the matter:
   
- oslo-spec was approved with narrowed scope which is now
'enabled mysqlconnector as an alternative in gate' instead of
'switch the default db driver to mysqlconnector'. We'll revisit
the switch part the next cycle once we have the new driver
running in gate and real benchmarking is heavy-lifted.
   
- there are several patches that are needed to make devstack
and tempest passing deployment and testing. Those are collected
under the hood of: https://review.openstack.org/#/c/114207/ Not
much of them.
   
- we'll need a new oslo.db release to bump versions (this is
needed to set raise_on_warnings=False for the new driver, which
was incorrectly set to True in sqlalchemy till very recently).
This is expected to be released this month (as per Roman
Podoliaka).
   
This release is currently blocked on landing some changes in
projects
   
using the library so they don?t break when the new version starts
using different exception classes. We?re tracking that work in
https://etherpad.openstack.org/p/sqla_exceptions_caught
   
It looks like we?re down to 2 patches, one for cinder
   
(https://review.openstack.org/#/c/111760/) and one for glance
(https://review.openstack.org/#/c/109655). Roman, can you verify
that those are the only two projects that need changes for the
exception issue?
   
- once the corresponding patch for sqlalchemy-migrate is
merged, we'll also need a new version released for this.
   
So we're going for a new version of sqlalchemy?  (We have a
separate workaround for raise_on_warnings that doesn't require the
new sqlalchemy release if this brings too many other issues)
  
   Wrong. We're going for a new version of *sqlalchemy-migrate*. Which is
   the code that we inherited from Mike and currently track in stackforge.
  
- on PyPI side, no news for now. The last time I've heard from
Geert (the maintainer of MySQL Connector for Python), he was
working on this. I suspect there are some legal considerations
running inside Oracle. I'll update once I know more about
that.
   
If we don?t have the new package on PyPI, how do we plan to
include it
   
in the gate? Are there options to allow an exception, or to make
the mirroring software download it anyway?
   
We can test via devstack without waiting for pypi, since devstack
will install via rpms/debs.
  
   I expect that it will be settled. I have no indication that the issue
   is unsolvable, it will just take a bit more time than we're accustomed
   to. :)
  
   At the moment, we install MySQLdb from distro packages for devstack.
   Same applies to new driver. It will be still great to see the package
   published on PyPI so that we can track its version requirements
   instead of relying on distros to package it properly. But I don't see
   it as a blocker.
  
   Also, we will probably be able to run with other drivers supported by
   SQLAlchemy once all the work is done.
 
  So I got bored last night and decided to take a stab at making PyMySQL
  work since I was a proponent of it earlier. Thankfully it did just
  mostly work like I thought it would.
  https://review.openstack.org/#/c/115495/ is the WIP devstack change to
  test this out.

 Thanks!

  Postgres tests fail because it was applying the pymysql driver to the
  postgres connection string. We can clean this up later in devstack
  and/or devstack-gate depending on how we need to apply this stuff.
  Bashate failed because I had to monkeypatch in a fix for a ceilometer
  issue loading sqlalchemy drivers. The tempest neutron full job fails on
  one test occasionally. Not sure yet if that is normal neutron full
  failure mode or if a new thing from PyMySQL. The regular tempest job
  passes just fine.
 
  There are also some DB related errors in the logs that will need to be
  cleaned up but overall it just works. So I would like to repropose that
  we stop focusing all of this effort on the hard thing and use the easy
  thing if it meets our needs. We can continue to make alternatives work,
  but that is a different problem that we can solve at a different pace. I
  am not sure how to test the neutron thing that Gus was running into
  though so we should also check that really quickly.

 TL;DR: pymysql passes my test case.
 I'm perfectly happy to move 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-21 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 21/08/14 02:03, Clark Boylan wrote:
 On Mon, Aug 18, 2014, at 01:59 AM, Ihar Hrachyshka wrote: On
 17/08/14 02:09, Angus Lees wrote:
 
 On 16 Aug 2014 06:09, Doug Hellmann d...@doughellmann.com
  mailto:d...@doughellmann.com wrote:
 
 
 On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka 
 ihrac...@redhat.com
 mailto:ihrac...@redhat.com wrote:
 
 Signed PGP part Some updates on the matter:
 
 - oslo-spec was approved with narrowed scope which is
 now 'enabled mysqlconnector as an alternative in gate'
 instead of 'switch the default db driver to
 mysqlconnector'. We'll revisit the switch part the next
 cycle once we have the new driver running in gate and
 real benchmarking is heavy-lifted.
 
 - there are several patches that are needed to make
 devstack and tempest passing deployment and testing.
 Those are collected under the hood of:
 https://review.openstack.org/#/c/114207/ Not much of
 them.
 
 - we'll need a new oslo.db release to bump versions (this
 is needed to set raise_on_warnings=False for the new
 driver, which was incorrectly set to True in sqlalchemy
 till very recently). This is expected to be released this
 month (as per Roman Podoliaka).
 
 This release is currently blocked on landing some changes
 in projects
 using the library so they don?t break when the new version
 starts using different exception classes. We?re tracking that
 work in 
 https://etherpad.openstack.org/p/sqla_exceptions_caught
 
 It looks like we?re down to 2 patches, one for cinder
 (https://review.openstack.org/#/c/111760/) and one for glance
  (https://review.openstack.org/#/c/109655). Roman, can you
 verify that those are the only two projects that need changes
 for the exception issue?
 
 
 - once the corresponding patch for sqlalchemy-migrate is 
 merged, we'll also need a new version released for this.
 
 So we're going for a new version of sqlalchemy?  (We have a 
 separate workaround for raise_on_warnings that doesn't
 require the new sqlalchemy release if this brings too many
 other issues)
 
 Wrong. We're going for a new version of *sqlalchemy-migrate*. Which
 is the code that we inherited from Mike and currently track in
 stackforge.
 
 
 - on PyPI side, no news for now. The last time I've heard
 from Geert (the maintainer of MySQL Connector for
 Python), he was working on this. I suspect there are some
 legal considerations running inside Oracle. I'll update
 once I know more about that.
 
 If we don?t have the new package on PyPI, how do we plan
 to include it
 in the gate? Are there options to allow an exception, or to
 make the mirroring software download it anyway?
 
 We can test via devstack without waiting for pypi, since
 devstack will install via rpms/debs.
 
 I expect that it will be settled. I have no indication that the
 issue is unsolvable, it will just take a bit more time than we're
 accustomed to. :)
 
 At the moment, we install MySQLdb from distro packages for
 devstack. Same applies to new driver. It will be still great to see
 the package published on PyPI so that we can track its version
 requirements instead of relying on distros to package it properly.
 But I don't see it as a blocker.
 
 Also, we will probably be able to run with other drivers supported
 by SQLAlchemy once all the work is done.
 
 So I got bored last night and decided to take a stab at making
 PyMySQL work since I was a proponent of it earlier. Thankfully it
 did just mostly work like I thought it would. 
 https://review.openstack.org/#/c/115495/ is the WIP devstack
 change to test this out.

Great!

 
 Postgres tests fail because it was applying the pymysql driver to
 the postgres connection string. We can clean this up later in
 devstack and/or devstack-gate depending on how we need to apply
 this stuff. Bashate failed because I had to monkeypatch in a
 fix for a ceilometer issue loading sqlalchemy drivers. The
 tempest neutron full job fails on one test occasionally. Not sure
 yet if that is normal neutron full failure mode or if a new thing
 from PyMySQL. The regular tempest job passes just fine.
 
 There are also some DB related errors in the logs that will need
 to be cleaned up but overall it just works. So I would like to
 repropose that we stop focusing all of this effort on the hard
 thing and use the easy thing if it meets our needs. We can
 continue to make alternatives work, but that is a different
 problem that we can solve at a different pace. I am not sure how
 to test the neutron thing that Gus was running into though so we
 should also check that really quickly.

In our patches througout the projects, we're actually not focusing on
any specific driver, even though the original spec is focused on MySQL
Connector. I still think we should achieve MySQL Connector working in
gate in the very near future. The current progress can be tracked at:

https://review.openstack.org/#/c/114207/

 
 Also, the tests themselves don't seem to run any faster or slower
 than 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-21 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 21/08/14 09:42, Endre Karlson wrote:
 Why pymysql over mysql-python?
 

http://specs.openstack.org/openstack/oslo-specs/specs/juno/enable-mysql-connector.html#problem-description
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-20 Thread Clark Boylan
On Mon, Aug 18, 2014, at 01:59 AM, Ihar Hrachyshka wrote:
 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA512
 
 On 17/08/14 02:09, Angus Lees wrote:
  
  On 16 Aug 2014 06:09, Doug Hellmann d...@doughellmann.com 
  mailto:d...@doughellmann.com wrote:
  
  
  On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka
  ihrac...@redhat.com
  mailto:ihrac...@redhat.com wrote:
  
  Signed PGP part Some updates on the matter:
  
  - oslo-spec was approved with narrowed scope which is now
  'enabled mysqlconnector as an alternative in gate' instead of
  'switch the default db driver to mysqlconnector'. We'll revisit
  the switch part the next cycle once we have the new driver
  running in gate and real benchmarking is heavy-lifted.
  
  - there are several patches that are needed to make devstack
  and tempest passing deployment and testing. Those are collected
  under the hood of: https://review.openstack.org/#/c/114207/ Not
  much of them.
  
  - we'll need a new oslo.db release to bump versions (this is
  needed to set raise_on_warnings=False for the new driver, which
  was incorrectly set to True in sqlalchemy till very recently).
  This is expected to be released this month (as per Roman
  Podoliaka).
  
  This release is currently blocked on landing some changes in
  projects
  using the library so they don?t break when the new version starts
  using different exception classes. We?re tracking that work in 
  https://etherpad.openstack.org/p/sqla_exceptions_caught
  
  It looks like we?re down to 2 patches, one for cinder
  (https://review.openstack.org/#/c/111760/) and one for glance 
  (https://review.openstack.org/#/c/109655). Roman, can you verify
  that those are the only two projects that need changes for the
  exception issue?
  
  
  - once the corresponding patch for sqlalchemy-migrate is
  merged, we'll also need a new version released for this.
  
  So we're going for a new version of sqlalchemy?  (We have a
  separate workaround for raise_on_warnings that doesn't require the
  new sqlalchemy release if this brings too many other issues)
 
 Wrong. We're going for a new version of *sqlalchemy-migrate*. Which is
 the code that we inherited from Mike and currently track in stackforge.
 
  
  - on PyPI side, no news for now. The last time I've heard from
  Geert (the maintainer of MySQL Connector for Python), he was
  working on this. I suspect there are some legal considerations
  running inside Oracle. I'll update once I know more about
  that.
  
  If we don?t have the new package on PyPI, how do we plan to
  include it
  in the gate? Are there options to allow an exception, or to make
  the mirroring software download it anyway?
  
  We can test via devstack without waiting for pypi, since devstack
  will install via rpms/debs.
 
 I expect that it will be settled. I have no indication that the issue
 is unsolvable, it will just take a bit more time than we're accustomed
 to. :)
 
 At the moment, we install MySQLdb from distro packages for devstack.
 Same applies to new driver. It will be still great to see the package
 published on PyPI so that we can track its version requirements
 instead of relying on distros to package it properly. But I don't see
 it as a blocker.
 
 Also, we will probably be able to run with other drivers supported by
 SQLAlchemy once all the work is done.
 
So I got bored last night and decided to take a stab at making PyMySQL
work since I was a proponent of it earlier. Thankfully it did just
mostly work like I thought it would.
https://review.openstack.org/#/c/115495/ is the WIP devstack change to
test this out.

Postgres tests fail because it was applying the pymysql driver to the
postgres connection string. We can clean this up later in devstack
and/or devstack-gate depending on how we need to apply this stuff.
Bashate failed because I had to monkeypatch in a fix for a ceilometer
issue loading sqlalchemy drivers. The tempest neutron full job fails on
one test occasionally. Not sure yet if that is normal neutron full
failure mode or if a new thing from PyMySQL. The regular tempest job
passes just fine.

There are also some DB related errors in the logs that will need to be
cleaned up but overall it just works. So I would like to repropose that
we stop focusing all of this effort on the hard thing and use the easy
thing if it meets our needs. We can continue to make alternatives work,
but that is a different problem that we can solve at a different pace. I
am not sure how to test the neutron thing that Gus was running into
though so we should also check that really quickly.

Also, the tests themselves don't seem to run any faster or slower than
when using the default mysql driver. Hard to complain about that :)

Clark
  
  - Gus
  
  
  
  ___ OpenStack-dev
  mailing list OpenStack-dev@lists.openstack.org 
  http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
  
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-18 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 17/08/14 02:09, Angus Lees wrote:
 
 On 16 Aug 2014 06:09, Doug Hellmann d...@doughellmann.com 
 mailto:d...@doughellmann.com wrote:
 
 
 On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka
 ihrac...@redhat.com
 mailto:ihrac...@redhat.com wrote:
 
 Signed PGP part Some updates on the matter:
 
 - oslo-spec was approved with narrowed scope which is now
 'enabled mysqlconnector as an alternative in gate' instead of
 'switch the default db driver to mysqlconnector'. We'll revisit
 the switch part the next cycle once we have the new driver
 running in gate and real benchmarking is heavy-lifted.
 
 - there are several patches that are needed to make devstack
 and tempest passing deployment and testing. Those are collected
 under the hood of: https://review.openstack.org/#/c/114207/ Not
 much of them.
 
 - we'll need a new oslo.db release to bump versions (this is
 needed to set raise_on_warnings=False for the new driver, which
 was incorrectly set to True in sqlalchemy till very recently).
 This is expected to be released this month (as per Roman
 Podoliaka).
 
 This release is currently blocked on landing some changes in
 projects
 using the library so they don?t break when the new version starts
 using different exception classes. We?re tracking that work in 
 https://etherpad.openstack.org/p/sqla_exceptions_caught
 
 It looks like we?re down to 2 patches, one for cinder
 (https://review.openstack.org/#/c/111760/) and one for glance 
 (https://review.openstack.org/#/c/109655). Roman, can you verify
 that those are the only two projects that need changes for the
 exception issue?
 
 
 - once the corresponding patch for sqlalchemy-migrate is
 merged, we'll also need a new version released for this.
 
 So we're going for a new version of sqlalchemy?  (We have a
 separate workaround for raise_on_warnings that doesn't require the
 new sqlalchemy release if this brings too many other issues)

Wrong. We're going for a new version of *sqlalchemy-migrate*. Which is
the code that we inherited from Mike and currently track in stackforge.

 
 - on PyPI side, no news for now. The last time I've heard from
 Geert (the maintainer of MySQL Connector for Python), he was
 working on this. I suspect there are some legal considerations
 running inside Oracle. I'll update once I know more about
 that.
 
 If we don?t have the new package on PyPI, how do we plan to
 include it
 in the gate? Are there options to allow an exception, or to make
 the mirroring software download it anyway?
 
 We can test via devstack without waiting for pypi, since devstack
 will install via rpms/debs.

I expect that it will be settled. I have no indication that the issue
is unsolvable, it will just take a bit more time than we're accustomed
to. :)

At the moment, we install MySQLdb from distro packages for devstack.
Same applies to new driver. It will be still great to see the package
published on PyPI so that we can track its version requirements
instead of relying on distros to package it properly. But I don't see
it as a blocker.

Also, we will probably be able to run with other drivers supported by
SQLAlchemy once all the work is done.

 
 - Gus
 
 
 
 ___ OpenStack-dev
 mailing list OpenStack-dev@lists.openstack.org 
 http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-18 Thread Victor Sergeyev
Hello Doug, All.

 This release is currently blocked on landing some changes in projects
using the library so they don’t break when the new version starts using
different exception classes. We’re tracking that work in
https://etherpad.openstack.org/p/sqla_exceptions_caught

 It looks like we’re down to 2 patches, one for cinder (
https://review.openstack.org/#/c/111760/) and one for glance (
https://review.openstack.org/#/c/109655).

At the moment these patches are merged, so the exception issue was fixed in
all core OS projects.

But unfortunately, there is another blocker for the oslo.db release - Heat
uses BaseMigrationTestCase class, which was removed from oslo.db in patch
https://review.openstack.org/#/c/93424/ , so the new oslo.db release will
break unittests in Heat. Here is the patch, which should fix this issue -
https://review.openstack.org/#/c/109658/

I really hope, that this patch is the last release blocker :)
Roman, folks - please fix me, if I miss something



On Fri, Aug 15, 2014 at 11:07 PM, Doug Hellmann d...@doughellmann.com
wrote:


 On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:

  Signed PGP part
  Some updates on the matter:
 
  - oslo-spec was approved with narrowed scope which is now 'enabled
  mysqlconnector as an alternative in gate' instead of 'switch the
  default db driver to mysqlconnector'. We'll revisit the switch part
  the next cycle once we have the new driver running in gate and real
  benchmarking is heavy-lifted.
 
  - there are several patches that are needed to make devstack and
  tempest passing deployment and testing. Those are collected under the
  hood of: https://review.openstack.org/#/c/114207/ Not much of them.
 
  - we'll need a new oslo.db release to bump versions (this is needed to
  set raise_on_warnings=False for the new driver, which was incorrectly
  set to True in sqlalchemy till very recently). This is expected to be
  released this month (as per Roman Podoliaka).

 This release is currently blocked on landing some changes in projects
 using the library so they don’t break when the new version starts using
 different exception classes. We’re tracking that work in
 https://etherpad.openstack.org/p/sqla_exceptions_caught

 It looks like we’re down to 2 patches, one for cinder (
 https://review.openstack.org/#/c/111760/) and one for glance (
 https://review.openstack.org/#/c/109655). Roman, can you verify that
 those are the only two projects that need changes for the exception issue?

 
  - once the corresponding patch for sqlalchemy-migrate is merged, we'll
  also need a new version released for this.
 
  - on PyPI side, no news for now. The last time I've heard from Geert
  (the maintainer of MySQL Connector for Python), he was working on
  this. I suspect there are some legal considerations running inside
  Oracle. I'll update once I know more about that.

 If we don’t have the new package on PyPI, how do we plan to include it in
 the gate? Are there options to allow an exception, or to make the mirroring
 software download it anyway?

 Doug

 
  - once all the relevant patches land in affected projects and
  devstack, I'm going to introduce a separate gate job to run against
  mysqlconnector.
 
  Cheers,
  /Ihar
 
  On 22/07/14 15:03, Ihar Hrachyshka wrote:
   FYI: I've moved the spec to oslo space since the switch is not
   really limited to neutron, and most of coding is to be done in
   oslo.db (though not much anyway).
  
   New spec: https://review.openstack.org/#/c/108355/
  
   On 09/07/14 13:17, Ihar Hrachyshka wrote:
   Hi all,
  
   Multiple projects are suffering from db lock timeouts due to
   deadlocks deep in mysqldb library that we use to interact with
   mysql servers. In essence, the problem is due to missing
   eventlet support in mysqldb module, meaning when a db lock is
   encountered, the library does not yield to the next green thread,
   allowing other threads to eventually unlock the grabbed lock, and
   instead it just blocks the main thread, that eventually raises
   timeout exception (OperationalError).
  
   The failed operation is not retried, leaving failing request not
served. In Nova, there is a special retry mechanism for
   deadlocks, though I think it's more a hack than a proper fix.
  
   Neutron is one of the projects that suffer from those timeout
   errors a lot. Partly it's due to lack of discipline in how we do
   nested calls in l3_db and ml2_plugin code, but that's not
   something to change in foreseeable future, so we need to find
   another solution that is applicable for Juno. Ideally, the
   solution should be applicable for Icehouse too to allow
   distributors to resolve existing deadlocks without waiting for
   Juno.
  
   We've had several discussions and attempts to introduce a
   solution to the problem. Thanks to oslo.db guys, we now have more
   or less clear view on the cause of the failures and how to easily
   fix them. The solution is to switch mysqldb to 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-16 Thread Angus Lees
On 16 Aug 2014 06:09, Doug Hellmann d...@doughellmann.com wrote:


 On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:

  Signed PGP part
  Some updates on the matter:
 
  - oslo-spec was approved with narrowed scope which is now 'enabled
  mysqlconnector as an alternative in gate' instead of 'switch the
  default db driver to mysqlconnector'. We'll revisit the switch part
  the next cycle once we have the new driver running in gate and real
  benchmarking is heavy-lifted.
 
  - there are several patches that are needed to make devstack and
  tempest passing deployment and testing. Those are collected under the
  hood of: https://review.openstack.org/#/c/114207/ Not much of them.
 
  - we'll need a new oslo.db release to bump versions (this is needed to
  set raise_on_warnings=False for the new driver, which was incorrectly
  set to True in sqlalchemy till very recently). This is expected to be
  released this month (as per Roman Podoliaka).

 This release is currently blocked on landing some changes in projects
using the library so they don’t break when the new version starts using
different exception classes. We’re tracking that work in
https://etherpad.openstack.org/p/sqla_exceptions_caught

 It looks like we’re down to 2 patches, one for cinder (
https://review.openstack.org/#/c/111760/) and one for glance (
https://review.openstack.org/#/c/109655). Roman, can you verify that those
are the only two projects that need changes for the exception issue?

 
  - once the corresponding patch for sqlalchemy-migrate is merged, we'll
  also need a new version released for this.

So we're going for a new version of sqlalchemy?  (We have a separate
workaround for raise_on_warnings that doesn't require the new sqlalchemy
release if this brings too many other issues)

  - on PyPI side, no news for now. The last time I've heard from Geert
  (the maintainer of MySQL Connector for Python), he was working on
  this. I suspect there are some legal considerations running inside
  Oracle. I'll update once I know more about that.

 If we don’t have the new package on PyPI, how do we plan to include it in
the gate? Are there options to allow an exception, or to make the mirroring
software download it anyway?

We can test via devstack without waiting for pypi, since devstack will
install via rpms/debs.

- Gus
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-15 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

Some updates on the matter:

- - oslo-spec was approved with narrowed scope which is now 'enabled
mysqlconnector as an alternative in gate' instead of 'switch the
default db driver to mysqlconnector'. We'll revisit the switch part
the next cycle once we have the new driver running in gate and real
benchmarking is heavy-lifted.

- - there are several patches that are needed to make devstack and
tempest passing deployment and testing. Those are collected under the
hood of: https://review.openstack.org/#/c/114207/ Not much of them.

- - we'll need a new oslo.db release to bump versions (this is needed to
set raise_on_warnings=False for the new driver, which was incorrectly
set to True in sqlalchemy till very recently). This is expected to be
released this month (as per Roman Podoliaka).

- - once the corresponding patch for sqlalchemy-migrate is merged, we'll
also need a new version released for this.

- - on PyPI side, no news for now. The last time I've heard from Geert
(the maintainer of MySQL Connector for Python), he was working on
this. I suspect there are some legal considerations running inside
Oracle. I'll update once I know more about that.

- - once all the relevant patches land in affected projects and
devstack, I'm going to introduce a separate gate job to run against
mysqlconnector.

Cheers,
/Ihar

On 22/07/14 15:03, Ihar Hrachyshka wrote:
 FYI: I've moved the spec to oslo space since the switch is not
 really limited to neutron, and most of coding is to be done in
 oslo.db (though not much anyway).
 
 New spec: https://review.openstack.org/#/c/108355/
 
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to 
 deadlocks deep in mysqldb library that we use to interact with 
 mysql servers. In essence, the problem is due to missing
 eventlet support in mysqldb module, meaning when a db lock is
 encountered, the library does not yield to the next green thread,
 allowing other threads to eventually unlock the grabbed lock, and
 instead it just blocks the main thread, that eventually raises
 timeout exception (OperationalError).
 
 The failed operation is not retried, leaving failing request not
  served. In Nova, there is a special retry mechanism for
 deadlocks, though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout 
 errors a lot. Partly it's due to lack of discipline in how we do 
 nested calls in l3_db and ml2_plugin code, but that's not
 something to change in foreseeable future, so we need to find
 another solution that is applicable for Juno. Ideally, the
 solution should be applicable for Icehouse too to allow
 distributors to resolve existing deadlocks without waiting for
 Juno.
 
 We've had several discussions and attempts to introduce a
 solution to the problem. Thanks to oslo.db guys, we now have more
 or less clear view on the cause of the failures and how to easily
 fix them. The solution is to switch mysqldb to something eventlet
 aware. The best candidate is probably MySQL Connector module that
 is an official MySQL client for Python and that shows some
 (preliminary) good results in terms of performance.
 
 I've posted a Neutron spec for the switch to the new client in
 Juno at [1]. Ideally, switch is just a matter of several fixes
 to oslo.db that would enable full support for the new driver
 already supported by SQLAlchemy, plus 'connection' string
 modified in service configuration files, plus documentation
 updates to refer to the new official way to configure services
 for MySQL. The database code won't, ideally, require any major
 changes, though some adaptation for the new client library may be
 needed. That said, Neutron does not seem to require any changes,
 though it was revealed that there are some alembic migration
 rules in Keystone or Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service 
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious
 wish to switch to the new library globally throughout all the
 projects, to reduce devops burden, among other things. My vision
 is that, ideally, we switch all projects to the new library in
 Juno, though we still may leave several projects for K in case
 any issues arise, similar to the way projects switched to
 oslo.messaging during two cycles instead of one. Though looking
 at how easy Neutron can be switched to the new library, I
 wouldn't expect any issues that would postpone the switch till
 K.
 
 It was mentioned in comments to the spec proposal that there
 were some discussions at the latest summit around possible switch
 in context of Nova that revealed some concerns, though they do
 not seem to be documented anywhere. So if you know anything about
 it, please comment.
 
 So, we'd like to hear from other projects what's your take on
 that move, 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-08-15 Thread Doug Hellmann

On Aug 15, 2014, at 9:29 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:

 Signed PGP part
 Some updates on the matter:
 
 - oslo-spec was approved with narrowed scope which is now 'enabled
 mysqlconnector as an alternative in gate' instead of 'switch the
 default db driver to mysqlconnector'. We'll revisit the switch part
 the next cycle once we have the new driver running in gate and real
 benchmarking is heavy-lifted.
 
 - there are several patches that are needed to make devstack and
 tempest passing deployment and testing. Those are collected under the
 hood of: https://review.openstack.org/#/c/114207/ Not much of them.
 
 - we'll need a new oslo.db release to bump versions (this is needed to
 set raise_on_warnings=False for the new driver, which was incorrectly
 set to True in sqlalchemy till very recently). This is expected to be
 released this month (as per Roman Podoliaka).

This release is currently blocked on landing some changes in projects using the 
library so they don’t break when the new version starts using different 
exception classes. We’re tracking that work in 
https://etherpad.openstack.org/p/sqla_exceptions_caught

It looks like we’re down to 2 patches, one for cinder 
(https://review.openstack.org/#/c/111760/) and one for glance 
(https://review.openstack.org/#/c/109655). Roman, can you verify that those are 
the only two projects that need changes for the exception issue?

 
 - once the corresponding patch for sqlalchemy-migrate is merged, we'll
 also need a new version released for this.
 
 - on PyPI side, no news for now. The last time I've heard from Geert
 (the maintainer of MySQL Connector for Python), he was working on
 this. I suspect there are some legal considerations running inside
 Oracle. I'll update once I know more about that.

If we don’t have the new package on PyPI, how do we plan to include it in the 
gate? Are there options to allow an exception, or to make the mirroring 
software download it anyway?

Doug

 
 - once all the relevant patches land in affected projects and
 devstack, I'm going to introduce a separate gate job to run against
 mysqlconnector.
 
 Cheers,
 /Ihar
 
 On 22/07/14 15:03, Ihar Hrachyshka wrote:
  FYI: I've moved the spec to oslo space since the switch is not
  really limited to neutron, and most of coding is to be done in
  oslo.db (though not much anyway).
 
  New spec: https://review.openstack.org/#/c/108355/
 
  On 09/07/14 13:17, Ihar Hrachyshka wrote:
  Hi all,
 
  Multiple projects are suffering from db lock timeouts due to
  deadlocks deep in mysqldb library that we use to interact with
  mysql servers. In essence, the problem is due to missing
  eventlet support in mysqldb module, meaning when a db lock is
  encountered, the library does not yield to the next green thread,
  allowing other threads to eventually unlock the grabbed lock, and
  instead it just blocks the main thread, that eventually raises
  timeout exception (OperationalError).
 
  The failed operation is not retried, leaving failing request not
   served. In Nova, there is a special retry mechanism for
  deadlocks, though I think it's more a hack than a proper fix.
 
  Neutron is one of the projects that suffer from those timeout
  errors a lot. Partly it's due to lack of discipline in how we do
  nested calls in l3_db and ml2_plugin code, but that's not
  something to change in foreseeable future, so we need to find
  another solution that is applicable for Juno. Ideally, the
  solution should be applicable for Icehouse too to allow
  distributors to resolve existing deadlocks without waiting for
  Juno.
 
  We've had several discussions and attempts to introduce a
  solution to the problem. Thanks to oslo.db guys, we now have more
  or less clear view on the cause of the failures and how to easily
  fix them. The solution is to switch mysqldb to something eventlet
  aware. The best candidate is probably MySQL Connector module that
  is an official MySQL client for Python and that shows some
  (preliminary) good results in terms of performance.
 
  I've posted a Neutron spec for the switch to the new client in
  Juno at [1]. Ideally, switch is just a matter of several fixes
  to oslo.db that would enable full support for the new driver
  already supported by SQLAlchemy, plus 'connection' string
  modified in service configuration files, plus documentation
  updates to refer to the new official way to configure services
  for MySQL. The database code won't, ideally, require any major
  changes, though some adaptation for the new client library may be
  needed. That said, Neutron does not seem to require any changes,
  though it was revealed that there are some alembic migration
  rules in Keystone or Glance that need (trivial) modifications.
 
  You can see how trivial the switch can be achieved for a service
  based on example for Neutron [2].
 
  While this is a Neutron specific proposal, there is an obvious
  wish to switch to the new library globally throughout 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-22 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

FYI: I've moved the spec to oslo space since the switch is not really
limited to neutron, and most of coding is to be done in oslo.db
(though not much anyway).

New spec: https://review.openstack.org/#/c/108355/

On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing other
 threads to eventually unlock the grabbed lock, and instead it just
 blocks the main thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving failing request not 
 served. In Nova, there is a special retry mechanism for deadlocks, 
 though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not something
 to change in foreseeable future, so we need to find another
 solution that is applicable for Juno. Ideally, the solution should
 be applicable for Icehouse too to allow distributors to resolve
 existing deadlocks without waiting for Juno.
 
 We've had several discussions and attempts to introduce a solution
 to the problem. Thanks to oslo.db guys, we now have more or less
 clear view on the cause of the failures and how to easily fix them.
 The solution is to switch mysqldb to something eventlet aware. The
 best candidate is probably MySQL Connector module that is an
 official MySQL client for Python and that shows some (preliminary)
 good results in terms of performance.
 
 I've posted a Neutron spec for the switch to the new client in Juno
 at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer to
 the new official way to configure services for MySQL. The database
 code won't, ideally, require any major changes, though some
 adaptation for the new client library may be needed. That said,
 Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone or
 Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious wish
 to switch to the new library globally throughout all the projects,
 to reduce devops burden, among other things. My vision is that,
 ideally, we switch all projects to the new library in Juno, though
 we still may leave several projects for K in case any issues arise,
 similar to the way projects switched to oslo.messaging during two
 cycles instead of one. Though looking at how easy Neutron can be
 switched to the new library, I wouldn't expect any issues that
 would postpone the switch till K.
 
 It was mentioned in comments to the spec proposal that there were
 some discussions at the latest summit around possible switch in
 context of Nova that revealed some concerns, though they do not
 seem to be documented anywhere. So if you know anything about it,
 please comment.
 
 So, we'd like to hear from other projects what's your take on that 
 move, whether you see any issues or have concerns about it.
 
 Thanks for your comments, /Ihar
 
 [1]: https://review.openstack.org/#/c/104905/ [2]:
 https://review.openstack.org/#/c/105209/
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-21 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512



On 21/07/14 04:53, Angus Lees wrote:
 Status, as I understand it:
 
 * oslo.db changes to support other mysql drivers:
 
 https://review.openstack.org/#/c/104425/  (merged) 
 https://review.openstack.org/#/c/106928/  (awaiting oslo.db
 review) https://review.openstack.org/#/c/107221/  (awaiting oslo.db
 review)

For that last one, the idea is correct, but the implementation is
wrong, see my comments in the review.

 
 (These are sufficient to allow operators to switch connection
 strings and use mysqlconnector.  The rest is all for our testing
 environment)
 
 * oslo.db change to allow testing with other mysql drivers:
 
 https://review.openstack.org/#/c/104428/  (awaiting oslo.db
 review) https://review.openstack.org/#/c/104447/  (awaiting oslo.db
 review. Ongoing discussion towards a larger rewrite of oslo.db
 testing instead)
 
 * Integration into jenkins environment:
 
 Blocked on getting Oracle to distribute mysql-connector via pypi. 
 Ihar and others are having conversations with the upstream author.
 
 * Devstack change to switch to mysqlconnector for neutron:
 
 https://review.openstack.org/#/c/105209/  (marked wip) Ihar: do you
 want me to pick this up, or are you going to continue it once some
 of the above has settled?

This is in WIP because it's not clear now whether the switch is
expected to be global or local to neutron. I'll make sure it's covered
if/when spec is approved.

 
 * oslo.db gate test that reproduces the deadlock with eventlet:
 
 https://review.openstack.org/#/c/104436/  (In review.  Can't be 
 submitted until gate environment is switched to mysqlconnector)
 

+ performance is yet to be benchmarked for different projects.

 
 Overall I'm not happy with the rate of change - but we're getting
 there.

That's Openstack! Changes take time here.

 I look forward to getting this fixed :/
 

Thanks for tracking oslo.db part of that, I really appreciate that.

 
 On 18 July 2014 21:45, Ihar Hrachyshka ihrac...@redhat.com 
 mailto:ihrac...@redhat.com wrote:
 
 On 14/07/14 17:03, Ihar Hrachyshka wrote:
 On 14/07/14 15:54, Clark Boylan wrote:
 On Sun, Jul 13, 2014 at 9:20 AM, Ihar Hrachyshka 
 ihrac...@redhat.com mailto:ihrac...@redhat.com wrote: On
 11/07/14 19:20, Clark Boylan
 wrote:
 Before we get too far ahead of ourselves mysql-connector 
 is not hosted on pypi. Instead it is an external package 
 link. We recently managed to remove all packages that
 are hosted as external package links from openstack and
 will not add new ones in. Before we can use
 mysql-connector in the gate oracle will need to publish
 mysql-connector on pypi properly.
 
 There is misunderstanding in our community on how we deploy db 
 client modules. No project actually depends on any of them. We 
 assume deployers will install the proper one and configure 
 'connection' string to use it. In case of devstack, we install 
 the appropriate package from distribution packages, not pip.
 
 Correct, but for all of the other test suites (unittests) we 
 install the db clients via pip because tox runs them and 
 virtualenvs allowing site packages cause too many problems.
 See
 
 
 https://git.openstack.org/cgit/openstack/nova/tree/test-requirements.txt#n8.



 
 
 So we do actually depend on these things being pip installable.
 Basically this allows devs to run `tox` and it works.
 
 Roger that, and thanks for clarification. I'm trying to reach
 the author and the maintainer of mysqlconnector-python to see
 whether I'll be able to convince him to publish the packages on 
 pypi.python.org http://pypi.python.org.
 
 
 I've reached the maintainer of the module, he told me he is
 currently working on uploading releases directly to
 pypi.python.org http://pypi.python.org.
 
 
 I would argue that we should have devstack install via pip
 too for consistency, but that is a different issue (it is
 already installing all of the other python dependencies this
 way so why special case?).
 
 What we do is recommending a module for our users in our 
 documentation.
 
 That said, I assume the gate is a non-issue. Correct?
 
 
 That said there is at least one other pure python 
 alternative, PyMySQL. PyMySQL supports py3k and pypy. We 
 should look at using PyMySQL instead if we want to start 
 with a reasonable path to getting this in the gate.
 
 MySQL Connector supports py3k too (not sure about pypy
 though).
 
 
 Clark
 
 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo
 Pelayo mangel...@redhat.com
 mailto:mangel...@redhat.com wrote:
 +1 here too,
 
 Amazed with the performance gains, x2.4 seems a lot,
 and we'd get rid of deadlocks.
 
 
 
 - Original Message -
 +1
 
 I'm pretty excited about the possibilities here.
 I've had this mysqldb/eventlet contention in the back
 of my mind for some time now. I'm glad to see some
 work being done in this area.
 
 Carl
 
 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka 
 ihrac...@redhat.com mailto:ihrac...@redhat.com
 wrote:
 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-20 Thread Angus Lees
Status, as I understand it:

* oslo.db changes to support other mysql drivers:

https://review.openstack.org/#/c/104425/  (merged)
https://review.openstack.org/#/c/106928/  (awaiting oslo.db review)
https://review.openstack.org/#/c/107221/  (awaiting oslo.db review)

(These are sufficient to allow operators to switch connection strings and
use mysqlconnector.  The rest is all for our testing environment)

* oslo.db change to allow testing with other mysql drivers:

https://review.openstack.org/#/c/104428/  (awaiting oslo.db review)
https://review.openstack.org/#/c/104447/  (awaiting oslo.db review.
 Ongoing discussion towards a larger rewrite of oslo.db testing instead)

* Integration into jenkins environment:

Blocked on getting Oracle to distribute mysql-connector via pypi.
Ihar and others are having conversations with the upstream author.

* Devstack change to switch to mysqlconnector for neutron:

https://review.openstack.org/#/c/105209/  (marked wip)
Ihar: do you want me to pick this up, or are you going to continue it once
some of the above has settled?

* oslo.db gate test that reproduces the deadlock with eventlet:

https://review.openstack.org/#/c/104436/  (In review.  Can't be submitted
until gate environment is switched to mysqlconnector)


Overall I'm not happy with the rate of change - but we're getting there.  I
look forward to getting this fixed :/


On 18 July 2014 21:45, Ihar Hrachyshka ihrac...@redhat.com wrote:

 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA512

 On 14/07/14 17:03, Ihar Hrachyshka wrote:
  On 14/07/14 15:54, Clark Boylan wrote:
  On Sun, Jul 13, 2014 at 9:20 AM, Ihar Hrachyshka
  ihrac...@redhat.com wrote: On 11/07/14 19:20, Clark Boylan
  wrote:
  Before we get too far ahead of ourselves mysql-connector
  is not hosted on pypi. Instead it is an external package
  link. We recently managed to remove all packages that are
  hosted as external package links from openstack and will
  not add new ones in. Before we can use mysql-connector in
  the gate oracle will need to publish mysql-connector on
  pypi properly.
 
  There is misunderstanding in our community on how we deploy db
  client modules. No project actually depends on any of them. We
  assume deployers will install the proper one and configure
  'connection' string to use it. In case of devstack, we install
  the appropriate package from distribution packages, not pip.
 
  Correct, but for all of the other test suites (unittests) we
  install the db clients via pip because tox runs them and
  virtualenvs allowing site packages cause too many problems. See
 
 
 https://git.openstack.org/cgit/openstack/nova/tree/test-requirements.txt#n8
 .
 
 
 
 
 So we do actually depend on these things being pip installable.
  Basically this allows devs to run `tox` and it works.
 
  Roger that, and thanks for clarification. I'm trying to reach the
  author and the maintainer of mysqlconnector-python to see whether
  I'll be able to convince him to publish the packages on
  pypi.python.org.
 

 I've reached the maintainer of the module, he told me he is currently
 working on uploading releases directly to pypi.python.org.

 
  I would argue that we should have devstack install via pip too
  for consistency, but that is a different issue (it is already
  installing all of the other python dependencies this way so
  why special case?).
 
  What we do is recommending a module for our users in our
  documentation.
 
  That said, I assume the gate is a non-issue. Correct?
 
 
  That said there is at least one other pure python
  alternative, PyMySQL. PyMySQL supports py3k and pypy. We
  should look at using PyMySQL instead if we want to start
  with a reasonable path to getting this in the gate.
 
  MySQL Connector supports py3k too (not sure about pypy though).
 
 
  Clark
 
  On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo
  mangel...@redhat.com wrote:
  +1 here too,
 
  Amazed with the performance gains, x2.4 seems a lot, and
  we'd get rid of deadlocks.
 
 
 
  - Original Message -
  +1
 
  I'm pretty excited about the possibilities here.  I've
  had this mysqldb/eventlet contention in the back of my
  mind for some time now. I'm glad to see some work
  being done in this area.
 
  Carl
 
  On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka
  ihrac...@redhat.com wrote:
  On 09/07/14 13:17, Ihar Hrachyshka wrote:
  Hi all,
 
  Multiple projects are suffering from db lock
  timeouts due to deadlocks deep in mysqldb
  library that we use to interact with mysql
  servers. In essence, the problem is due to
  missing eventlet support in mysqldb module,
  meaning when a db lock is encountered, the
  library does not yield to the next green thread,
  allowing other threads to eventually unlock the
  grabbed lock, and instead it just blocks the main
  thread, that eventually raises timeout exception
  (OperationalError).
 
  The failed operation is not retried, leaving
  failing request not served. In Nova, there is a
  

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-18 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 14/07/14 17:03, Ihar Hrachyshka wrote:
 On 14/07/14 15:54, Clark Boylan wrote:
 On Sun, Jul 13, 2014 at 9:20 AM, Ihar Hrachyshka 
 ihrac...@redhat.com wrote: On 11/07/14 19:20, Clark Boylan 
 wrote:
 Before we get too far ahead of ourselves mysql-connector
 is not hosted on pypi. Instead it is an external package
 link. We recently managed to remove all packages that are
 hosted as external package links from openstack and will
 not add new ones in. Before we can use mysql-connector in
 the gate oracle will need to publish mysql-connector on
 pypi properly.
 
 There is misunderstanding in our community on how we deploy db 
 client modules. No project actually depends on any of them. We 
 assume deployers will install the proper one and configure 
 'connection' string to use it. In case of devstack, we install
 the appropriate package from distribution packages, not pip.
 
 Correct, but for all of the other test suites (unittests) we 
 install the db clients via pip because tox runs them and 
 virtualenvs allowing site packages cause too many problems. See
  
 https://git.openstack.org/cgit/openstack/nova/tree/test-requirements.txt#n8.



 
So we do actually depend on these things being pip installable.
 Basically this allows devs to run `tox` and it works.
 
 Roger that, and thanks for clarification. I'm trying to reach the 
 author and the maintainer of mysqlconnector-python to see whether
 I'll be able to convince him to publish the packages on
 pypi.python.org.
 

I've reached the maintainer of the module, he told me he is currently
working on uploading releases directly to pypi.python.org.

 
 I would argue that we should have devstack install via pip too 
 for consistency, but that is a different issue (it is already 
 installing all of the other python dependencies this way so
 why special case?).
 
 What we do is recommending a module for our users in our 
 documentation.
 
 That said, I assume the gate is a non-issue. Correct?
 
 
 That said there is at least one other pure python 
 alternative, PyMySQL. PyMySQL supports py3k and pypy. We 
 should look at using PyMySQL instead if we want to start
 with a reasonable path to getting this in the gate.
 
 MySQL Connector supports py3k too (not sure about pypy though).
 
 
 Clark
 
 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo 
 mangel...@redhat.com wrote:
 +1 here too,
 
 Amazed with the performance gains, x2.4 seems a lot, and 
 we'd get rid of deadlocks.
 
 
 
 - Original Message -
 +1
 
 I'm pretty excited about the possibilities here.  I've 
 had this mysqldb/eventlet contention in the back of my 
 mind for some time now. I'm glad to see some work
 being done in this area.
 
 Carl
 
 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka 
 ihrac...@redhat.com wrote:
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock 
 timeouts due to deadlocks deep in mysqldb
 library that we use to interact with mysql
 servers. In essence, the problem is due to
 missing eventlet support in mysqldb module,
 meaning when a db lock is encountered, the
 library does not yield to the next green thread,
 allowing other threads to eventually unlock the
 grabbed lock, and instead it just blocks the main
 thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving 
 failing request not served. In Nova, there is a 
 special retry mechanism for deadlocks, though I 
 think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from 
 those timeout errors a lot. Partly it's due to
 lack of discipline in how we do nested calls in
 l3_db and ml2_plugin code, but that's not
 something to change in foreseeable future, so we
 need to find another solution that is applicable
 for Juno. Ideally, the solution should be
 applicable for Icehouse too to allow distributors
 to resolve existing deadlocks without waiting for
 Juno.
 
 We've had several discussions and attempts to 
 introduce a solution to the problem. Thanks to 
 oslo.db guys, we now have more or less clear
 view on the cause of the failures and how to
 easily fix them. The solution is to switch
 mysqldb to something eventlet aware. The best
 candidate is probably MySQL Connector module that
 is an official MySQL client for Python and that
 shows some (preliminary) good results in terms
 of performance.
 
 I've made additional testing, creating 2000 networks in 
 parallel (10 thread workers) for both drivers and
 comparing results.
 
 With mysqldb: 215.81 sec With mysql-connector: 88.66
 
 ~2.4 times performance boost, ok? ;)
 
 I think we should switch to that library *even* if we
 forget about all the nasty deadlocks we experience now.
 
 
 I've posted a Neutron spec for the switch to the 
 new client in Juno at [1]. Ideally, switch is
 just a matter of several fixes to oslo.db that
 would enable full support for the new 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-16 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 16/07/14 01:50, Vishvananda Ishaya wrote:
 
 On Jul 15, 2014, at 3:30 PM, Ihar Hrachyshka ihrac...@redhat.com
 wrote:
 
 Signed PGP part On 14/07/14 22:48, Vishvananda Ishaya wrote:
 
 On Jul 13, 2014, at 9:29 AM, Ihar Hrachyshka
 ihrac...@redhat.com wrote:
 
 Signed PGP part On 12/07/14 03:17, Mike Bayer wrote:
 
 On 7/11/14, 7:26 PM, Carl Baldwin wrote:
 
 
 On Jul 11, 2014 5:32 PM, Vishvananda Ishaya 
 vishvana...@gmail.com
 mailto:vishvana...@gmail.com wrote:
 
 I have tried using pymysql in place of mysqldb and in
 real world
 concurrency
 tests against cinder and nova it performs slower. I
 was inspired by
 the mention
 of mysql-connector so I just tried that option
 instead.
 Mysql-connector seems
 to be slightly slower as well, which leads me to
 believe that the
 blocking inside of
 
 Do you have some numbers?  Seems to be slightly slower 
 doesn't
 really stand up as an argument against the numbers that
 have been posted in this thread.
 
 Numbers are highly dependent on a number of other factors, but
 I was seeing 100 concurrent list commands against cinder going
 from an average of 400 ms to an average of around 600 ms with
 both msql-connector and pymsql.
 
 I've made my tests on neutron only, so there is possibility that 
 cinder works somehow differently.
 
 But, those numbers don't tell a lot in terms of considering the 
 switch. Do you have numbers for mysqldb case?
 
 Sorry if my commentary above was unclear. The  400ms is mysqldb. 
 The 600ms average was the same for both the other options.
 
 
 It is also worth mentioning that my test of 100 concurrent
 creates from the same project in cinder leads to average
 response times over 3 seconds. Note that creates return before
 the request is sent to the node for processing, so this is just
 the api creating the db record and sticking a message on the
 queue. A huge part of the slowdown is in quota reservation
 processing which does a row lock on the project id.
 
 Again, are those 3 seconds better or worse than what we have for
 mysqldb?
 
 The 3 seconds is from mysqldb. I don?t have average response times
 for mysql-connector due to the timeouts I mention below.
 
 
 Before we are sure that an eventlet friendly backend ?gets rid
 of all deadlocks?, I will mention that trying this test
 against connector leads to some requests timing out at our load
 balancer (5 minute timeout), so we may actually be introducing
 deadlocks where the retry_on_deadlock operator is used.
 
 Deadlocks != timeouts. I attempt to fix eventlet-triggered db 
 deadlocks, not all possible deadlocks that you may envision, or
 timeouts.
 
 That may be true, but if switching the default is trading one
 problem for another it isn?t necessarily the right fix. The timeout
 means that one or more greenthreads are never actually generating a
 response. I suspect and endless retry_on_deadlock between a couple
 of competing greenthreads which we don?t hit with mysqldb, but it
 could be any number of things.
 
 
 
 Consider the above anecdotal for the moment, since I can?t
 verify for sure that switching the sql driver didn?t introduce
 some other race or unrelated problem.
 
 Let me just caution that we can?t recommend replacing our
 mysql backend without real performance and load testing.
 
 I agree. Not saying that the tests are somehow complete, but here
 is what I was into last two days.
 
 There is a nice openstack project called Rally that is designed
 to allow easy benchmarks for openstack projects. They have four
 scenarios for neutron implemented: for networks, ports, routers,
 and subnets. Each scenario combines create and list commands.
 
 I've run each test with the following runner settings: times =
 100, concurrency = 10, meaning each scenario is run 100 times in
 parallel, and there were not more than 10 parallel scenarios
 running. Then I've repeated the same for times = 100, concurrency
 = 20 (also set max_pool_size to 20 to allow sqlalchemy utilize
 that level of parallelism), and times = 1000, concurrency = 100
 (same note on sqlalchemy parallelism).
 
 You can find detailed html files with nice graphs here [1].
 Brief description of results is below:
 
 1. create_and_list_networks scenario: for 10 parallel workers 
 performance boost is -12.5% from original time, for 20 workers
 -6.3%, for 100 workers there is a slight reduction of average
 time spent for scenario +9.4% (this is the only scenario that
 showed slight reduction in performance, I'll try to rerun the
 test tomorrow to see whether it was some discrepancy when I
 executed it that influenced the result).
 
 2. create_and_list_ports scenario: for 10 parallel workers boost
 is -25.8%, for 20 workers it's -9.4%, and for 100 workers it's
 -12.6%.
 
 3. create_and_list_routers scenario: for 10 parallel workers
 boost is -46.6% (almost half of original time), for 20 workers
 it's -51.7% (more than a half), for 100 workers it's -41.5%.
 
 4. 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-15 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 14/07/14 22:48, Vishvananda Ishaya wrote:
 
 On Jul 13, 2014, at 9:29 AM, Ihar Hrachyshka ihrac...@redhat.com
 wrote:
 
 Signed PGP part On 12/07/14 03:17, Mike Bayer wrote:
 
 On 7/11/14, 7:26 PM, Carl Baldwin wrote:
 
 
 On Jul 11, 2014 5:32 PM, Vishvananda Ishaya 
 vishvana...@gmail.com
 mailto:vishvana...@gmail.com wrote:
 
 I have tried using pymysql in place of mysqldb and in real 
 world
 concurrency
 tests against cinder and nova it performs slower. I was 
 inspired by
 the mention
 of mysql-connector so I just tried that option instead.
 Mysql-connector seems
 to be slightly slower as well, which leads me to believe
 that the
 blocking inside of
 
 Do you have some numbers?  Seems to be slightly slower
 doesn't
 really stand up as an argument against the numbers that have
 been posted in this thread.
 
 Numbers are highly dependent on a number of other factors, but I
 was seeing 100 concurrent list commands against cinder going from
 an average of 400 ms to an average of around 600 ms with both
 msql-connector and pymsql.

I've made my tests on neutron only, so there is possibility that
cinder works somehow differently.

But, those numbers don't tell a lot in terms of considering the
switch. Do you have numbers for mysqldb case?

 
 It is also worth mentioning that my test of 100 concurrent creates
 from the same project in cinder leads to average response times
 over 3 seconds. Note that creates return before the request is sent
 to the node for processing, so this is just the api creating the db
 record and sticking a message on the queue. A huge part of the
 slowdown is in quota reservation processing which does a row lock
 on the project id.

Again, are those 3 seconds better or worse than what we have for mysqldb?

 
 Before we are sure that an eventlet friendly backend “gets rid of
 all deadlocks”, I will mention that trying this test against
 connector leads to some requests timing out at our load balancer (5
 minute timeout), so we may actually be introducing deadlocks where
 the retry_on_deadlock operator is used.

Deadlocks != timeouts. I attempt to fix eventlet-triggered db
deadlocks, not all possible deadlocks that you may envision, or timeouts.

 
 Consider the above anecdotal for the moment, since I can’t verify
 for sure that switching the sql driver didn’t introduce some other
 race or unrelated problem.
 
 Let me just caution that we can’t recommend replacing our mysql
 backend without real performance and load testing.

I agree. Not saying that the tests are somehow complete, but here is
what I was into last two days.

There is a nice openstack project called Rally that is designed to
allow easy benchmarks for openstack projects. They have four scenarios
for neutron implemented: for networks, ports, routers, and subnets.
Each scenario combines create and list commands.

I've run each test with the following runner settings: times = 100,
concurrency = 10, meaning each scenario is run 100 times in parallel,
and there were not more than 10 parallel scenarios running. Then I've
repeated the same for times = 100, concurrency = 20 (also set
max_pool_size to 20 to allow sqlalchemy utilize that level of
parallelism), and times = 1000, concurrency = 100 (same note on
sqlalchemy parallelism).

You can find detailed html files with nice graphs here [1]. Brief
description of results is below:

1. create_and_list_networks scenario: for 10 parallel workers
performance boost is -12.5% from original time, for 20 workers -6.3%,
for 100 workers there is a slight reduction of average time spent for
scenario +9.4% (this is the only scenario that showed slight reduction
in performance, I'll try to rerun the test tomorrow to see whether it
was some discrepancy when I executed it that influenced the result).

2. create_and_list_ports scenario: for 10 parallel workers boost is
- -25.8%, for 20 workers it's -9.4%, and for 100 workers it's -12.6%.

3. create_and_list_routers scenario: for 10 parallel workers boost is
- -46.6% (almost half of original time), for 20 workers it's -51.7%
(more than a half), for 100 workers it's -41.5%.

4. create_and_list_subnets scenario: for 10 parallel workers boost is
- -26.4%, for 20 workers it's -51.1% (more than half reduction in time
spent for average scenario), and for 100 workers it's -31.7%.

I've tried to check how it scales till 200 parallel workers, but was
hit by local file opened limits and mysql max_connection settings. I
will retry my tests with limits raised tomorrow to see how it handles
that huge load.

Tomorrow I will also try to test new library with multiple API workers.

Other than that, what are your suggestions on what to check/test?

FYI: [1] contains the following directories:

mysqlconnector/
mysqldb/

Each of them contains the following directories:
10-10/ - 10 parallel workers, max_pool_size = 10 (default)
20-100/ - 20 parallel workers, max_pool_size = 100
100-100/ - 100 parallel workers, 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-15 Thread Vishvananda Ishaya

On Jul 15, 2014, at 3:30 PM, Ihar Hrachyshka ihrac...@redhat.com wrote:

 Signed PGP part
 On 14/07/14 22:48, Vishvananda Ishaya wrote:
 
  On Jul 13, 2014, at 9:29 AM, Ihar Hrachyshka ihrac...@redhat.com
  wrote:
 
  Signed PGP part On 12/07/14 03:17, Mike Bayer wrote:
 
  On 7/11/14, 7:26 PM, Carl Baldwin wrote:
 
 
  On Jul 11, 2014 5:32 PM, Vishvananda Ishaya
  vishvana...@gmail.com
  mailto:vishvana...@gmail.com wrote:
 
  I have tried using pymysql in place of mysqldb and in real
  world
  concurrency
  tests against cinder and nova it performs slower. I was
  inspired by
  the mention
  of mysql-connector so I just tried that option instead.
  Mysql-connector seems
  to be slightly slower as well, which leads me to believe
  that the
  blocking inside of
 
  Do you have some numbers?  Seems to be slightly slower
  doesn't
  really stand up as an argument against the numbers that have
  been posted in this thread.
 
  Numbers are highly dependent on a number of other factors, but I
  was seeing 100 concurrent list commands against cinder going from
  an average of 400 ms to an average of around 600 ms with both
  msql-connector and pymsql.
 
 I've made my tests on neutron only, so there is possibility that
 cinder works somehow differently.
 
 But, those numbers don't tell a lot in terms of considering the
 switch. Do you have numbers for mysqldb case?

Sorry if my commentary above was unclear. The  400ms is mysqldb.
The 600ms average was the same for both the other options.
 
 
  It is also worth mentioning that my test of 100 concurrent creates
  from the same project in cinder leads to average response times
  over 3 seconds. Note that creates return before the request is sent
  to the node for processing, so this is just the api creating the db
  record and sticking a message on the queue. A huge part of the
  slowdown is in quota reservation processing which does a row lock
  on the project id.
 
 Again, are those 3 seconds better or worse than what we have for mysqldb?

The 3 seconds is from mysqldb. I don’t have average response times for
mysql-connector due to the timeouts I mention below.
 
 
  Before we are sure that an eventlet friendly backend “gets rid of
  all deadlocks”, I will mention that trying this test against
  connector leads to some requests timing out at our load balancer (5
  minute timeout), so we may actually be introducing deadlocks where
  the retry_on_deadlock operator is used.
 
 Deadlocks != timeouts. I attempt to fix eventlet-triggered db
 deadlocks, not all possible deadlocks that you may envision, or timeouts.

That may be true, but if switching the default is trading one problem
for another it isn’t necessarily the right fix. The timeout means that
one or more greenthreads are never actually generating a response. I suspect
and endless retry_on_deadlock between a couple of competing greenthreads
which we don’t hit with mysqldb, but it could be any number of things.

 
 
  Consider the above anecdotal for the moment, since I can’t verify
  for sure that switching the sql driver didn’t introduce some other
  race or unrelated problem.
 
  Let me just caution that we can’t recommend replacing our mysql
  backend without real performance and load testing.
 
 I agree. Not saying that the tests are somehow complete, but here is
 what I was into last two days.
 
 There is a nice openstack project called Rally that is designed to
 allow easy benchmarks for openstack projects. They have four scenarios
 for neutron implemented: for networks, ports, routers, and subnets.
 Each scenario combines create and list commands.
 
 I've run each test with the following runner settings: times = 100,
 concurrency = 10, meaning each scenario is run 100 times in parallel,
 and there were not more than 10 parallel scenarios running. Then I've
 repeated the same for times = 100, concurrency = 20 (also set
 max_pool_size to 20 to allow sqlalchemy utilize that level of
 parallelism), and times = 1000, concurrency = 100 (same note on
 sqlalchemy parallelism).
 
 You can find detailed html files with nice graphs here [1]. Brief
 description of results is below:
 
 1. create_and_list_networks scenario: for 10 parallel workers
 performance boost is -12.5% from original time, for 20 workers -6.3%,
 for 100 workers there is a slight reduction of average time spent for
 scenario +9.4% (this is the only scenario that showed slight reduction
 in performance, I'll try to rerun the test tomorrow to see whether it
 was some discrepancy when I executed it that influenced the result).
 
 2. create_and_list_ports scenario: for 10 parallel workers boost is
 -25.8%, for 20 workers it's -9.4%, and for 100 workers it's -12.6%.
 
 3. create_and_list_routers scenario: for 10 parallel workers boost is
 -46.6% (almost half of original time), for 20 workers it's -51.7%
 (more than a half), for 100 workers it's -41.5%.
 
 4. create_and_list_subnets scenario: for 10 parallel workers boost is
 -26.4%, for 20 workers 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-14 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 14/07/14 07:45, Thomas Goirand wrote:
 On 07/14/2014 12:20 AM, Ihar Hrachyshka wrote:
 On 11/07/14 19:20, Clark Boylan wrote:
 That said there is at least one other pure python alternative,
  PyMySQL. PyMySQL supports py3k and pypy. We should look at
 using PyMySQL instead if we want to start with a reasonable
 path to getting this in the gate.
 
 MySQL Connector supports py3k too (not sure about pypy though).
 
 Yes, and it's also what Django people recommend:
 
 https://docs.djangoproject.com/en/1.7/ref/databases/#mysql-db-api-drivers

  As for mysqldb and Python3, the only way is to use a Python 3 fork
 such as this one: https://github.com/clelland/MySQL-for-Python-3
 
 I wouldn't like using different versions of Python modules
 depending on the Python version, and therefore,
 python-mysql.connector / python3-mysql.connector would be
 preferred.
 
 However, it'd be nice if *all* projects could switch to that, and
 not just Neutron, otherwise, we'd be just adding a new dependency,
 which isn't great.

Yes, we envision global switch, though some projects may choose to
wait for another cycle to see how it works for pioneers.

 
 Also, about eventlet, there's been long threads about switching to 
 something else like asyncio. Wouldn't it be time to also do that
 (at the same time)?

Eventlet has lots of flaws, though I don't see it replaced by asyncio
or any other mechanism this or even the next cycle.

There is lots of work to do to replace it. Switching mysql library is
a 100 line patch + performance benchmarking to avoid regression.
Switching async library is thousands of LOC + refactoring + very
significant work on oslo side.

 
 Cheers,
 
 Thomas Goirand (zigo)
 
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 http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-14 Thread Clark Boylan
On Sun, Jul 13, 2014 at 9:20 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:
 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA512

 On 11/07/14 19:20, Clark Boylan wrote:
 Before we get too far ahead of ourselves mysql-connector is not
 hosted on pypi. Instead it is an external package link. We recently
 managed to remove all packages that are hosted as external package
 links from openstack and will not add new ones in. Before we can
 use mysql-connector in the gate oracle will need to publish
 mysql-connector on pypi properly.

 There is misunderstanding in our community on how we deploy db client
 modules. No project actually depends on any of them. We assume
 deployers will install the proper one and configure 'connection'
 string to use it. In case of devstack, we install the appropriate
 package from distribution packages, not pip.

Correct, but for all of the other test suites (unittests) we install
the db clients via pip because tox runs them and virtualenvs allowing
site packages cause too many problems. See
https://git.openstack.org/cgit/openstack/nova/tree/test-requirements.txt#n8.
So we do actually depend on these things being pip installable.
Basically this allows devs to run `tox` and it works.

I would argue that we should have devstack install via pip too for
consistency, but that is a different issue (it is already installing
all of the other python dependencies this way so why special case?).

 What we do is recommending a module for our users in our documentation.

 That said, I assume the gate is a non-issue. Correct?


 That said there is at least one other pure python alternative,
 PyMySQL. PyMySQL supports py3k and pypy. We should look at using
 PyMySQL instead if we want to start with a reasonable path to
 getting this in the gate.

 MySQL Connector supports py3k too (not sure about pypy though).


 Clark

 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo
 mangel...@redhat.com wrote:
 +1 here too,

 Amazed with the performance gains, x2.4 seems a lot, and we'd get
 rid of deadlocks.



 - Original Message -
 +1

 I'm pretty excited about the possibilities here.  I've had
 this mysqldb/eventlet contention in the back of my mind for
 some time now. I'm glad to see some work being done in this
 area.

 Carl

 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka
 ihrac...@redhat.com wrote:
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,

 Multiple projects are suffering from db lock timeouts due
 to deadlocks deep in mysqldb library that we use to
 interact with mysql servers. In essence, the problem is
 due to missing eventlet support in mysqldb module,
 meaning when a db lock is encountered, the library does
 not yield to the next green thread, allowing other
 threads to eventually unlock the grabbed lock, and
 instead it just blocks the main thread, that eventually
 raises timeout exception (OperationalError).

 The failed operation is not retried, leaving failing
 request not served. In Nova, there is a special retry
 mechanism for deadlocks, though I think it's more a hack
 than a proper fix.

 Neutron is one of the projects that suffer from those
 timeout errors a lot. Partly it's due to lack of
 discipline in how we do nested calls in l3_db and
 ml2_plugin code, but that's not something to change in
 foreseeable future, so we need to find another solution
 that is applicable for Juno. Ideally, the solution
 should be applicable for Icehouse too to allow
 distributors to resolve existing deadlocks without
 waiting for Juno.

 We've had several discussions and attempts to introduce a
 solution to the problem. Thanks to oslo.db guys, we now
 have more or less clear view on the cause of the failures
 and how to easily fix them. The solution is to switch
 mysqldb to something eventlet aware. The best candidate
 is probably MySQL Connector module that is an official
 MySQL client for Python and that shows some
 (preliminary) good results in terms of performance.

 I've made additional testing, creating 2000 networks in parallel
 (10 thread workers) for both drivers and comparing results.

 With mysqldb: 215.81 sec With mysql-connector: 88.66

 ~2.4 times performance boost, ok? ;)

 I think we should switch to that library *even* if we forget about
 all the nasty deadlocks we experience now.


 I've posted a Neutron spec for the switch to the new
 client in Juno at [1]. Ideally, switch is just a matter
 of several fixes to oslo.db that would enable full
 support for the new driver already supported by
 SQLAlchemy, plus 'connection' string modified in service
 configuration files, plus documentation updates to refer
 to the new official way to configure services for MySQL.
 The database code won't, ideally, require any major
 changes, though some adaptation for the new client
 library may be needed. That said, Neutron does not seem
 to require any changes, though it was revealed that there
 are some alembic migration rules in Keystone or Glance
 that need (trivial) 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-14 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 14/07/14 15:54, Clark Boylan wrote:
 On Sun, Jul 13, 2014 at 9:20 AM, Ihar Hrachyshka
 ihrac...@redhat.com wrote: On 11/07/14 19:20, Clark Boylan
 wrote:
 Before we get too far ahead of ourselves mysql-connector is
 not hosted on pypi. Instead it is an external package link.
 We recently managed to remove all packages that are hosted as
 external package links from openstack and will not add new
 ones in. Before we can use mysql-connector in the gate oracle
 will need to publish mysql-connector on pypi properly.
 
 There is misunderstanding in our community on how we deploy db
 client modules. No project actually depends on any of them. We
 assume deployers will install the proper one and configure
 'connection' string to use it. In case of devstack, we install the
 appropriate package from distribution packages, not pip.
 
 Correct, but for all of the other test suites (unittests) we
 install the db clients via pip because tox runs them and
 virtualenvs allowing site packages cause too many problems. See 
 https://git.openstack.org/cgit/openstack/nova/tree/test-requirements.txt#n8.

 
So we do actually depend on these things being pip installable.
 Basically this allows devs to run `tox` and it works.

Roger that, and thanks for clarification. I'm trying to reach the
author and the maintainer of mysqlconnector-python to see whether I'll
be able to convince him to publish the packages on pypi.python.org.

 
 I would argue that we should have devstack install via pip too
 for consistency, but that is a different issue (it is already
 installing all of the other python dependencies this way so why
 special case?).
 
 What we do is recommending a module for our users in our
 documentation.
 
 That said, I assume the gate is a non-issue. Correct?
 
 
 That said there is at least one other pure python
 alternative, PyMySQL. PyMySQL supports py3k and pypy. We
 should look at using PyMySQL instead if we want to start with
 a reasonable path to getting this in the gate.
 
 MySQL Connector supports py3k too (not sure about pypy though).
 
 
 Clark
 
 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo 
 mangel...@redhat.com wrote:
 +1 here too,
 
 Amazed with the performance gains, x2.4 seems a lot, and
 we'd get rid of deadlocks.
 
 
 
 - Original Message -
 +1
 
 I'm pretty excited about the possibilities here.  I've
 had this mysqldb/eventlet contention in the back of my
 mind for some time now. I'm glad to see some work being
 done in this area.
 
 Carl
 
 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka 
 ihrac...@redhat.com wrote:
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock
 timeouts due to deadlocks deep in mysqldb library
 that we use to interact with mysql servers. In
 essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock
 is encountered, the library does not yield to the
 next green thread, allowing other threads to
 eventually unlock the grabbed lock, and instead it
 just blocks the main thread, that eventually raises
 timeout exception (OperationalError).
 
 The failed operation is not retried, leaving
 failing request not served. In Nova, there is a
 special retry mechanism for deadlocks, though I
 think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from
 those timeout errors a lot. Partly it's due to lack
 of discipline in how we do nested calls in l3_db
 and ml2_plugin code, but that's not something to
 change in foreseeable future, so we need to find
 another solution that is applicable for Juno.
 Ideally, the solution should be applicable for
 Icehouse too to allow distributors to resolve
 existing deadlocks without waiting for Juno.
 
 We've had several discussions and attempts to
 introduce a solution to the problem. Thanks to
 oslo.db guys, we now have more or less clear view
 on the cause of the failures and how to easily fix
 them. The solution is to switch mysqldb to
 something eventlet aware. The best candidate is
 probably MySQL Connector module that is an
 official MySQL client for Python and that shows
 some (preliminary) good results in terms of
 performance.
 
 I've made additional testing, creating 2000 networks in
 parallel (10 thread workers) for both drivers and comparing
 results.
 
 With mysqldb: 215.81 sec With mysql-connector: 88.66
 
 ~2.4 times performance boost, ok? ;)
 
 I think we should switch to that library *even* if we forget
 about all the nasty deadlocks we experience now.
 
 
 I've posted a Neutron spec for the switch to the
 new client in Juno at [1]. Ideally, switch is just
 a matter of several fixes to oslo.db that would
 enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string
 modified in service configuration files, plus
 documentation updates to refer to the new official
 way to configure services for MySQL. The 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-14 Thread Vishvananda Ishaya

On Jul 13, 2014, at 9:29 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:

 Signed PGP part
 On 12/07/14 03:17, Mike Bayer wrote:
 
  On 7/11/14, 7:26 PM, Carl Baldwin wrote:
 
 
  On Jul 11, 2014 5:32 PM, Vishvananda Ishaya
  vishvana...@gmail.com
  mailto:vishvana...@gmail.com wrote:
 
  I have tried using pymysql in place of mysqldb and in real
  world
  concurrency
  tests against cinder and nova it performs slower. I was
  inspired by
  the mention
  of mysql-connector so I just tried that option instead.
  Mysql-connector seems
  to be slightly slower as well, which leads me to believe that
  the
  blocking inside of
 
  Do you have some numbers?  Seems to be slightly slower doesn't
  really stand up as an argument against the numbers that have been
  posted in this thread.

Numbers are highly dependent on a number of other factors, but I was
seeing 100 concurrent list commands against cinder going from an average
of 400 ms to an average of around 600 ms with both msql-connector and pymsql.

It is also worth mentioning that my test of 100 concurrent creates from the
same project in cinder leads to average response times over 3 seconds. Note that
creates return before the request is sent to the node for processing, so
this is just the api creating the db record and sticking a message on the queue.
A huge part of the slowdown is in quota reservation processing which does a row
lock on the project id.

Before we are sure that an eventlet friendly backend “gets rid of all 
deadlocks”, I will
mention that trying this test against connector leads to some requests timing 
out
at our load balancer (5 minute timeout), so we may actually be introducing 
deadlocks
where the retry_on_deadlock operator is used.

Consider the above anecdotal for the moment, since I can’t verify for sure that
switching the sql driver didn’t introduce some other race or unrelated problem.

Let me just caution that we can’t recommend replacing our mysql backend without
real performance and load testing.

Vish

 
  sqlalchemy is not the main bottleneck across projects.
 
  Vish
 
  P.S. The performanace in all cases was abysmal, so performance
  work
  definitely
  needs to be done, but just the guess that replacing our mysql
  library is going to
  solve all of our performance problems appears to be incorrect
  at
  first blush.
 
  The motivation is still mostly deadlock relief but more
  performance
  work should be done.  I agree with you there.  I'm still hopeful
  for some improvement from this.
 
 
  To identify performance that's alleviated by async you have to
  establish up front that IO blocking is the issue, which would
  entail having code that's blazing fast until you start running it
  against concurrent connections, at which point you can identify via
  profiling that IO operations are being serialized.   This is a very
  specific issue.
 
  In contrast, to identify why some arbitrary openstack app is slow,
  my bet is that async is often not the big issue.   Every day I look
  at openstack code and talk to people working on things,  I see
  many performance issues that have nothing to do with concurrency,
  and as I detailed in my wiki page at
  https://wiki.openstack.org/wiki/OpenStack_and_SQLAlchemy there is a
  long road to cleaning up all the excessive queries, hundreds of
  unnecessary rows and columns being pulled over the network,
  unindexed lookups, subquery joins, hammering of Python-intensive
  operations (often due to the nature of OS apps as lots and lots of
  tiny API calls) that can be cached.   There's a clear path to tons
  better performance documented there and most of it is not about
  async  - which means that successful async isn't going to solve all
  those issues.
 
 
 Of course there is a long road to decent performance, and switching a
 library won't magically fix all out issues. But if it will fix
 deadlocks, and give 30% to 150% performance boost for different
 operations, and since the switch is almost smooth, this is something
 worth doing.
 
 
 
 
  ___ OpenStack-dev
  mailing list OpenStack-dev@lists.openstack.org
  http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
 
 
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-13 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 11/07/14 19:20, Clark Boylan wrote:
 Before we get too far ahead of ourselves mysql-connector is not
 hosted on pypi. Instead it is an external package link. We recently
 managed to remove all packages that are hosted as external package
 links from openstack and will not add new ones in. Before we can
 use mysql-connector in the gate oracle will need to publish 
 mysql-connector on pypi properly.

There is misunderstanding in our community on how we deploy db client
modules. No project actually depends on any of them. We assume
deployers will install the proper one and configure 'connection'
string to use it. In case of devstack, we install the appropriate
package from distribution packages, not pip.

What we do is recommending a module for our users in our documentation.

That said, I assume the gate is a non-issue. Correct?

 
 That said there is at least one other pure python alternative, 
 PyMySQL. PyMySQL supports py3k and pypy. We should look at using 
 PyMySQL instead if we want to start with a reasonable path to
 getting this in the gate.

MySQL Connector supports py3k too (not sure about pypy though).

 
 Clark
 
 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo 
 mangel...@redhat.com wrote:
 +1 here too,
 
 Amazed with the performance gains, x2.4 seems a lot, and we'd get
 rid of deadlocks.
 
 
 
 - Original Message -
 +1
 
 I'm pretty excited about the possibilities here.  I've had
 this mysqldb/eventlet contention in the back of my mind for
 some time now. I'm glad to see some work being done in this
 area.
 
 Carl
 
 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka
 ihrac...@redhat.com wrote:
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due
 to deadlocks deep in mysqldb library that we use to
 interact with mysql servers. In essence, the problem is
 due to missing eventlet support in mysqldb module,
 meaning when a db lock is encountered, the library does
 not yield to the next green thread, allowing other 
 threads to eventually unlock the grabbed lock, and
 instead it just blocks the main thread, that eventually
 raises timeout exception (OperationalError).
 
 The failed operation is not retried, leaving failing
 request not served. In Nova, there is a special retry
 mechanism for deadlocks, though I think it's more a hack
 than a proper fix.
 
 Neutron is one of the projects that suffer from those
 timeout errors a lot. Partly it's due to lack of
 discipline in how we do nested calls in l3_db and
 ml2_plugin code, but that's not something to change in
 foreseeable future, so we need to find another solution
 that is applicable for Juno. Ideally, the solution
 should be applicable for Icehouse too to allow
 distributors to resolve existing deadlocks without
 waiting for Juno.
 
 We've had several discussions and attempts to introduce a
 solution to the problem. Thanks to oslo.db guys, we now
 have more or less clear view on the cause of the failures
 and how to easily fix them. The solution is to switch
 mysqldb to something eventlet aware. The best candidate
 is probably MySQL Connector module that is an official
 MySQL client for Python and that shows some
 (preliminary) good results in terms of performance.
 
 I've made additional testing, creating 2000 networks in parallel
 (10 thread workers) for both drivers and comparing results.
 
 With mysqldb: 215.81 sec With mysql-connector: 88.66
 
 ~2.4 times performance boost, ok? ;)
 
 I think we should switch to that library *even* if we forget about
 all the nasty deadlocks we experience now.
 
 
 I've posted a Neutron spec for the switch to the new
 client in Juno at [1]. Ideally, switch is just a matter
 of several fixes to oslo.db that would enable full
 support for the new driver already supported by
 SQLAlchemy, plus 'connection' string modified in service
 configuration files, plus documentation updates to refer
 to the new official way to configure services for MySQL.
 The database code won't, ideally, require any major
 changes, though some adaptation for the new client
 library may be needed. That said, Neutron does not seem
 to require any changes, though it was revealed that there
 are some alembic migration rules in Keystone or Glance
 that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a
 service based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an
 obvious wish to switch to the new library globally
 throughout all the projects, to reduce devops burden,
 among other things. My vision is that, ideally, we switch
 all projects to the new library in Juno, though we still
 may leave several projects for K in case any issues
 arise, similar to the way projects switched to
 oslo.messaging during two cycles instead of one. Though
 looking at how easy Neutron can be switched to the new
 library, I wouldn't expect any issues 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-13 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 12/07/14 03:17, Mike Bayer wrote:
 
 On 7/11/14, 7:26 PM, Carl Baldwin wrote:
 
 
 On Jul 11, 2014 5:32 PM, Vishvananda Ishaya
 vishvana...@gmail.com
 mailto:vishvana...@gmail.com wrote:
 
 I have tried using pymysql in place of mysqldb and in real
 world
 concurrency
 tests against cinder and nova it performs slower. I was
 inspired by
 the mention
 of mysql-connector so I just tried that option instead.
 Mysql-connector seems
 to be slightly slower as well, which leads me to believe that
 the
 blocking inside of
 
 Do you have some numbers?  Seems to be slightly slower doesn't
 really stand up as an argument against the numbers that have been
 posted in this thread.
 
 sqlalchemy is not the main bottleneck across projects.
 
 Vish
 
 P.S. The performanace in all cases was abysmal, so performance
 work
 definitely
 needs to be done, but just the guess that replacing our mysql
 library is going to
 solve all of our performance problems appears to be incorrect
 at
 first blush.
 
 The motivation is still mostly deadlock relief but more
 performance
 work should be done.  I agree with you there.  I'm still hopeful
 for some improvement from this.
 
 
 To identify performance that's alleviated by async you have to
 establish up front that IO blocking is the issue, which would
 entail having code that's blazing fast until you start running it
 against concurrent connections, at which point you can identify via
 profiling that IO operations are being serialized.   This is a very
 specific issue.
 
 In contrast, to identify why some arbitrary openstack app is slow,
 my bet is that async is often not the big issue.   Every day I look
 at openstack code and talk to people working on things,  I see
 many performance issues that have nothing to do with concurrency,
 and as I detailed in my wiki page at 
 https://wiki.openstack.org/wiki/OpenStack_and_SQLAlchemy there is a
 long road to cleaning up all the excessive queries, hundreds of
 unnecessary rows and columns being pulled over the network,
 unindexed lookups, subquery joins, hammering of Python-intensive
 operations (often due to the nature of OS apps as lots and lots of
 tiny API calls) that can be cached.   There's a clear path to tons
 better performance documented there and most of it is not about
 async  - which means that successful async isn't going to solve all
 those issues.
 

Of course there is a long road to decent performance, and switching a
library won't magically fix all out issues. But if it will fix
deadlocks, and give 30% to 150% performance boost for different
operations, and since the switch is almost smooth, this is something
worth doing.

 
 
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-13 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 12/07/14 00:30, Vishvananda Ishaya wrote:
 I have tried using pymysql in place of mysqldb and in real world
 concurrency tests against cinder and nova it performs slower. I was
 inspired by the mention of mysql-connector so I just tried that
 option instead. Mysql-connector seems to be slightly slower as
 well, which leads me to believe that the blocking inside of 
 sqlalchemy is not the main bottleneck across projects.

I wonder what's your setup and library versions, and your script that
you use for testing would also be great to see.

In my tests, mysql-connector showed similar performance to what
mysqldb provides in serial testing. Once you get to parallel requests
execution, that's where the real benefit of parallelism shows up. Have
you run your testing with parallel requests in mind?

I now realise that I should have posted the benchmark I've used myself
in the first place. So here it is, as a gist:
https://gist.github.com/booxter/c4f3e743a2573ba7809f

 
 Vish
 
 P.S. The performanace in all cases was abysmal, so performance work
 definitely needs to be done, but just the guess that replacing our
 mysql library is going to solve all of our performance problems
 appears to be incorrect at first blush.

All? Not at all. Some of them? Probably.

That said, the primary reason to switch the library is avoiding
database deadlocks. Additional performance boost is just a nice thing
to have with little effort.

 
 On Jul 11, 2014, at 10:20 AM, Clark Boylan clark.boy...@gmail.com
 wrote:
 
 Before we get too far ahead of ourselves mysql-connector is not
 hosted on pypi. Instead it is an external package link. We
 recently managed to remove all packages that are hosted as
 external package links from openstack and will not add new ones
 in. Before we can use mysql-connector in the gate oracle will
 need to publish mysql-connector on pypi properly.
 
 That said there is at least one other pure python alternative, 
 PyMySQL. PyMySQL supports py3k and pypy. We should look at using 
 PyMySQL instead if we want to start with a reasonable path to
 getting this in the gate.
 
 Clark
 
 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo 
 mangel...@redhat.com wrote:
 +1 here too,
 
 Amazed with the performance gains, x2.4 seems a lot, and we'd
 get rid of deadlocks.
 
 
 
 - Original Message -
 +1
 
 I'm pretty excited about the possibilities here.  I've had
 this mysqldb/eventlet contention in the back of my mind for
 some time now. I'm glad to see some work being done in this
 area.
 
 Carl
 
 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka
 ihrac...@redhat.com wrote:
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts
 due to deadlocks deep in mysqldb library that we use to
 interact with mysql servers. In essence, the problem is
 due to missing eventlet support in mysqldb module,
 meaning when a db lock is encountered, the library does
 not yield to the next green thread, allowing other 
 threads to eventually unlock the grabbed lock, and
 instead it just blocks the main thread, that eventually
 raises timeout exception (OperationalError).
 
 The failed operation is not retried, leaving failing
 request not served. In Nova, there is a special retry
 mechanism for deadlocks, though I think it's more a
 hack than a proper fix.
 
 Neutron is one of the projects that suffer from those
 timeout errors a lot. Partly it's due to lack of
 discipline in how we do nested calls in l3_db and
 ml2_plugin code, but that's not something to change in
 foreseeable future, so we need to find another solution
 that is applicable for Juno. Ideally, the solution
 should be applicable for Icehouse too to allow
 distributors to resolve existing deadlocks without
 waiting for Juno.
 
 We've had several discussions and attempts to introduce
 a solution to the problem. Thanks to oslo.db guys, we
 now have more or less clear view on the cause of the
 failures and how to easily fix them. The solution is to
 switch mysqldb to something eventlet aware. The best
 candidate is probably MySQL Connector module that is
 an official MySQL client for Python and that shows some
 (preliminary) good results in terms of performance.
 
 I've made additional testing, creating 2000 networks in parallel
 (10 thread workers) for both drivers and comparing results.
 
 With mysqldb: 215.81 sec With mysql-connector: 88.66
 
 ~2.4 times performance boost, ok? ;)
 
 I think we should switch to that library *even* if we forget about
 all the nasty deadlocks we experience now.
 
 
 I've posted a Neutron spec for the switch to the new
 client in Juno at [1]. Ideally, switch is just a matter
 of several fixes to oslo.db that would enable full
 support for the new driver already supported by
 SQLAlchemy, plus 'connection' string modified in 
 service configuration files, plus documentation updates
 to refer to the new official way to configure 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-13 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 12/07/14 02:49, Jay Pipes wrote:
 On 07/11/2014 08:04 AM, Ihar Hrachyshka wrote: On 09/07/14 13:17,
 Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to 
 deadlocks deep in mysqldb library that we use to interact
 with mysql servers. In essence, the problem is due to missing
 eventlet support in mysqldb module, meaning when a db lock is
 encountered, the library does not yield to the next green
 thread, allowing other threads to eventually unlock the
 grabbed lock, and instead it just blocks the main thread,
 that eventually raises timeout exception (OperationalError).
 
 The failed operation is not retried, leaving failing request
 not served. In Nova, there is a special retry mechanism for
 deadlocks, though I think it's more a hack than a proper
 fix.
 
 Neutron is one of the projects that suffer from those
 timeout errors a lot. Partly it's due to lack of discipline
 in how we do nested calls in l3_db and ml2_plugin code, but
 that's not something to change in foreseeable future, so we
 need to find another solution that is applicable for Juno.
 Ideally, the solution should be applicable for Icehouse too
 to allow distributors to resolve existing deadlocks without
 waiting for Juno.
 
 We've had several discussions and attempts to introduce a
 solution to the problem. Thanks to oslo.db guys, we now have
 more or less clear view on the cause of the failures and how
 to easily fix them. The solution is to switch mysqldb to
 something eventlet aware. The best candidate is probably
 MySQL Connector module that is an official MySQL client for
 Python and that shows some (preliminary) good results in
 terms of performance.
 
 I've made additional testing, creating 2000 networks in parallel
 (10 thread workers) for both drivers and comparing results.
 
 With mysqldb: 215.81 sec With mysql-connector: 88.66
 
 ~2.4 times performance boost, ok? ;)
 
 That really doesn't tell me much.
 
 Please remember that performance != scalability.

I actually agree. I need to spend more time preparing benchmarks (I'll
spend a part of my next week on this).

 
 If you showed the test/benchmark code, that would be great. You
 need to

Here is a gist: https://gist.github.com/booxter/c4f3e743a2573ba7809f

 run your benchmarks at varying levels of concurrency and varying
 levels of read/write ratios for the workers. Otherwise it's like
 looking at a a single dot of paint on a painting. Without looking
 at the patterns of throughput (performance) and
 concurrency/locking (scalability) with various levels of workers
 and read/write ratios, you miss the whole picture.

Good point. I surely need to check read operations, and play with
multiple API/RPC workers.

Before I go with implementing my own tests, do you have more formal
requirements or suggestions on which data points we can be interested in?

 
 Another thing to ensure is that you are using real *processes*,
 not threads, so that you actually simulate a real OpenStack
 service like Nova or Neutron, which are multi-plexed, not
 multi-threaded, and have a greenlet pool within each worker
 process.

My test is an actual neutron client that issues full blown REST
requests to a local neutron server, in multiple thread workers. I
think this is ok, right?

 
 Best -jay
 
 I think we should switch to that library *even* if we forget about
 all the nasty deadlocks we experience now.
 
 
 I've posted a Neutron spec for the switch to the new client
 in Juno at [1]. Ideally, switch is just a matter of several
 fixes to oslo.db that would enable full support for the new
 driver already supported by SQLAlchemy, plus 'connection'
 string modified in service configuration files, plus
 documentation updates to refer to the new official way to
 configure services for MySQL. The database code won't,
 ideally, require any major changes, though some adaptation
 for the new client library may be needed. That said, Neutron
 does not seem to require any changes, though it was revealed
 that there are some alembic migration rules in Keystone or 
 Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a
 service based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an
 obvious wish to switch to the new library globally throughout
 all the projects, to reduce devops burden, among other
 things. My vision is that, ideally, we switch all projects to
 the new library in Juno, though we still may leave several
 projects for K in case any issues arise, similar to the way
 projects switched to oslo.messaging during two cycles instead
 of one. Though looking at how easy Neutron can be switched to
 the new library, I wouldn't expect any issues that would
 postpone the switch till K.
 
 It was mentioned in comments to the spec proposal that there
 were some discussions at the latest summit around possible
 switch in context of Nova that 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-13 Thread Thomas Goirand
On 07/14/2014 12:20 AM, Ihar Hrachyshka wrote:
 On 11/07/14 19:20, Clark Boylan wrote:
 That said there is at least one other pure python alternative, 
 PyMySQL. PyMySQL supports py3k and pypy. We should look at using 
 PyMySQL instead if we want to start with a reasonable path to
 getting this in the gate.
 
 MySQL Connector supports py3k too (not sure about pypy though).

Yes, and it's also what Django people recommend:

https://docs.djangoproject.com/en/1.7/ref/databases/#mysql-db-api-drivers

As for mysqldb and Python3, the only way is to use a Python 3 fork such
as this one:
https://github.com/clelland/MySQL-for-Python-3

I wouldn't like using different versions of Python modules depending on
the Python version, and therefore, python-mysql.connector /
python3-mysql.connector would be preferred.

However, it'd be nice if *all* projects could switch to that, and not
just Neutron, otherwise, we'd be just adding a new dependency, which
isn't great.

Also, about eventlet, there's been long threads about switching to
something else like asyncio. Wouldn't it be time to also do that (at the
same time)?

Cheers,

Thomas Goirand (zigo)

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-12 Thread Carl Baldwin
+1. Well put.  No one is arguing against this other approach.  The two
efforts can be taken independently.

Carl
On Jul 11, 2014 10:48 PM, Mike Bayer mba...@redhat.com wrote:


 On 7/11/14, 11:26 PM, Jay Pipes wrote:
  Yep, couldn't agree more.
 
  Frankly, the steps you outline in the wiki above are excellent
  examples of where we can make significant gains in both performance
  and scalability. In addition to those you listed, the underlying
  database schemas themselves, with the excessive use of large VARCHAR
  fields, BLOB fields for JSONified values, and the general bad strategy
  of bunching heavily-read fields with infrequently-read fields in the
  same tables, are also a source of poor overall database performance.
 Well the topic of schema modifications I actually left out of that
 document entirely for starters - I made a conscious choice to focus
 entirely on things that don't involve any apps changing any of their
 fundamental approaches or schemas...at least just yet! :)I'm hoping
 that as oslo.db improves and the patterns start to roll out, we can
 start working on schema design too.Because yeah I've seen the giant
 lists of VARCHAR everything and just said, OK well we're going to have
 to get to that..just not right now :).



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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing other
 threads to eventually unlock the grabbed lock, and instead it just
 blocks the main thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving failing request not 
 served. In Nova, there is a special retry mechanism for deadlocks, 
 though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not something
 to change in foreseeable future, so we need to find another
 solution that is applicable for Juno. Ideally, the solution should
 be applicable for Icehouse too to allow distributors to resolve
 existing deadlocks without waiting for Juno.
 
 We've had several discussions and attempts to introduce a solution
 to the problem. Thanks to oslo.db guys, we now have more or less
 clear view on the cause of the failures and how to easily fix them.
 The solution is to switch mysqldb to something eventlet aware. The
 best candidate is probably MySQL Connector module that is an
 official MySQL client for Python and that shows some (preliminary)
 good results in terms of performance.

I've made additional testing, creating 2000 networks in parallel (10
thread workers) for both drivers and comparing results.

With mysqldb: 215.81 sec
With mysql-connector: 88.66

~2.4 times performance boost, ok? ;)

I think we should switch to that library *even* if we forget about all
the nasty deadlocks we experience now.

 
 I've posted a Neutron spec for the switch to the new client in Juno
 at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer to
 the new official way to configure services for MySQL. The database
 code won't, ideally, require any major changes, though some
 adaptation for the new client library may be needed. That said,
 Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone or
 Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious wish
 to switch to the new library globally throughout all the projects,
 to reduce devops burden, among other things. My vision is that,
 ideally, we switch all projects to the new library in Juno, though
 we still may leave several projects for K in case any issues arise,
 similar to the way projects switched to oslo.messaging during two
 cycles instead of one. Though looking at how easy Neutron can be
 switched to the new library, I wouldn't expect any issues that
 would postpone the switch till K.
 
 It was mentioned in comments to the spec proposal that there were
 some discussions at the latest summit around possible switch in
 context of Nova that revealed some concerns, though they do not
 seem to be documented anywhere. So if you know anything about it,
 please comment.
 
 So, we'd like to hear from other projects what's your take on that 
 move, whether you see any issues or have concerns about it.
 
 Thanks for your comments, /Ihar
 
 [1]: https://review.openstack.org/#/c/104905/ [2]:
 https://review.openstack.org/#/c/105209/
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Mike Bayer

On 7/9/14, 10:59 AM, Roman Podoliaka wrote:
 Hi all,

 Not sure what issues you are talking about, but I just replaced
 mysql with mysql+mysqlconnector in my db connection string  in
 neutron.conf and neutron-db-manage upgrade head worked like a charm
 for an empty schema.

 Ihar, could please elaborate on what changes to oslo.db are needed?
 (as an oslo.db developer I'm very interested in this part :) )

 Thanks,
 Roman

 On Wed, Jul 9, 2014 at 5:43 PM, Ihar Hrachyshka ihrac...@redhat.com
wrote:
 On 09/07/14 15:40, Sean Dague wrote:
  On 07/09/2014 09:00 AM, Roman Podoliaka wrote:
  Hi Ihar,
 
  AFAIU, the switch is a matter of pip install + specifying the
  correct db URI in the config files. I'm not sure why you are
  filing a spec in Neutron project. IMHO, this has nothing to do
  with projects, but rather a purely deployment question. E.g.
  don't we have PostgreSQL+psycopg2 or MySQL+pymysql deployments of
  OpenStack right now?
 
  I think what you really want is to change the defaults we test in
  the gate, which is a different problem.
 
  Because this is really a *new* driver. As you can see by the
  attempted run, it doesn't work with alembic given the definitions
  that neutron has. So it's not like this is currently compatible
  with OpenStack code.

 Well, to fix that, you just need to specify raise_on_warnings=False
 for connection (it's default for mysqldb but not mysql-connector).
 I've done it in devstack patch for now, but probably it belongs to

this is also semi-my fault as mysqlconnector apparently defaults this to
False now, but for some reason the SQLAlchemy mysqlconnector dialect is
flipping it to True (this dialect was contributed by MySQL-connector's
folks, so not sure why the inconsistency, perhaps they changed their minds)



 oslo.db.

 
 
  Thanks, Roman
 
  On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka
  ihrac...@redhat.com wrote: Hi all,
 
  Multiple projects are suffering from db lock timeouts due to
  deadlocks deep in mysqldb library that we use to interact with
  mysql servers. In essence, the problem is due to missing eventlet
  support in mysqldb module, meaning when a db lock is encountered,
  the library does not yield to the next green thread, allowing
  other threads to eventually unlock the grabbed lock, and instead
  it just blocks the main thread, that eventually raises timeout
  exception (OperationalError).
 
  The failed operation is not retried, leaving failing request not
  served. In Nova, there is a special retry mechanism for
  deadlocks, though I think it's more a hack than a proper fix.
 
  Neutron is one of the projects that suffer from those timeout
  errors a lot. Partly it's due to lack of discipline in how we do
  nested calls in l3_db and ml2_plugin code, but that's not
  something to change in foreseeable future, so we need to find
  another solution that is applicable for Juno. Ideally, the
  solution should be applicable for Icehouse too to allow
  distributors to resolve existing deadlocks without waiting for
  Juno.
 
  We've had several discussions and attempts to introduce a
  solution to the problem. Thanks to oslo.db guys, we now have more
  or less clear view on the cause of the failures and how to easily
  fix them. The solution is to switch mysqldb to something eventlet
  aware. The best candidate is probably MySQL Connector module that
  is an official MySQL client for Python and that shows some
  (preliminary) good results in terms of performance.
 
  I've posted a Neutron spec for the switch to the new client in
  Juno at [1]. Ideally, switch is just a matter of several fixes to
  oslo.db that would enable full support for the new driver already
  supported by SQLAlchemy, plus 'connection' string modified in
  service configuration files, plus documentation updates to refer
  to the new official way to configure services for MySQL. The
  database code won't, ideally, require any major changes, though
  some adaptation for the new client library may be needed. That
  said, Neutron does not seem to require any changes, though it was
  revealed that there are some alembic migration rules in Keystone
  or Glance that need (trivial) modifications.
 
  You can see how trivial the switch can be achieved for a service
  based on example for Neutron [2].
 
  While this is a Neutron specific proposal, there is an obvious
  wish to switch to the new library globally throughout all the
  projects, to reduce devops burden, among other things. My vision
  is that, ideally, we switch all projects to the new library in
  Juno, though we still may leave several projects for K in case
  any issues arise, similar to the way projects switched to
  oslo.messaging during two cycles instead of one. Though looking
  at how easy Neutron can be switched to the new library, I
  wouldn't expect any issues that would postpone the switch till
  K.
 
  It was mentioned in comments to the spec proposal that there were
  some discussions at the latest summit 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Clark Boylan
Before we get too far ahead of ourselves mysql-connector is not hosted
on pypi. Instead it is an external package link. We recently managed
to remove all packages that are hosted as external package links from
openstack and will not add new ones in. Before we can use
mysql-connector in the gate oracle will need to publish
mysql-connector on pypi properly.

That said there is at least one other pure python alternative,
PyMySQL. PyMySQL supports py3k and pypy. We should look at using
PyMySQL instead if we want to start with a reasonable path to getting
this in the gate.

Clark

On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo
mangel...@redhat.com wrote:
 +1 here too,

 Amazed with the performance gains, x2.4 seems a lot,
 and we'd get rid of deadlocks.



 - Original Message -
 +1

 I'm pretty excited about the possibilities here.  I've had this
 mysqldb/eventlet contention in the back of my mind for some time now.
 I'm glad to see some work being done in this area.

 Carl

 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka ihrac...@redhat.com wrote:
  -BEGIN PGP SIGNED MESSAGE-
  Hash: SHA512
 
  On 09/07/14 13:17, Ihar Hrachyshka wrote:
  Hi all,
 
  Multiple projects are suffering from db lock timeouts due to
  deadlocks deep in mysqldb library that we use to interact with
  mysql servers. In essence, the problem is due to missing eventlet
  support in mysqldb module, meaning when a db lock is encountered,
  the library does not yield to the next green thread, allowing other
  threads to eventually unlock the grabbed lock, and instead it just
  blocks the main thread, that eventually raises timeout exception
  (OperationalError).
 
  The failed operation is not retried, leaving failing request not
  served. In Nova, there is a special retry mechanism for deadlocks,
  though I think it's more a hack than a proper fix.
 
  Neutron is one of the projects that suffer from those timeout
  errors a lot. Partly it's due to lack of discipline in how we do
  nested calls in l3_db and ml2_plugin code, but that's not something
  to change in foreseeable future, so we need to find another
  solution that is applicable for Juno. Ideally, the solution should
  be applicable for Icehouse too to allow distributors to resolve
  existing deadlocks without waiting for Juno.
 
  We've had several discussions and attempts to introduce a solution
  to the problem. Thanks to oslo.db guys, we now have more or less
  clear view on the cause of the failures and how to easily fix them.
  The solution is to switch mysqldb to something eventlet aware. The
  best candidate is probably MySQL Connector module that is an
  official MySQL client for Python and that shows some (preliminary)
  good results in terms of performance.
 
  I've made additional testing, creating 2000 networks in parallel (10
  thread workers) for both drivers and comparing results.
 
  With mysqldb: 215.81 sec
  With mysql-connector: 88.66
 
  ~2.4 times performance boost, ok? ;)
 
  I think we should switch to that library *even* if we forget about all
  the nasty deadlocks we experience now.
 
 
  I've posted a Neutron spec for the switch to the new client in Juno
  at [1]. Ideally, switch is just a matter of several fixes to
  oslo.db that would enable full support for the new driver already
  supported by SQLAlchemy, plus 'connection' string modified in
  service configuration files, plus documentation updates to refer to
  the new official way to configure services for MySQL. The database
  code won't, ideally, require any major changes, though some
  adaptation for the new client library may be needed. That said,
  Neutron does not seem to require any changes, though it was
  revealed that there are some alembic migration rules in Keystone or
  Glance that need (trivial) modifications.
 
  You can see how trivial the switch can be achieved for a service
  based on example for Neutron [2].
 
  While this is a Neutron specific proposal, there is an obvious wish
  to switch to the new library globally throughout all the projects,
  to reduce devops burden, among other things. My vision is that,
  ideally, we switch all projects to the new library in Juno, though
  we still may leave several projects for K in case any issues arise,
  similar to the way projects switched to oslo.messaging during two
  cycles instead of one. Though looking at how easy Neutron can be
  switched to the new library, I wouldn't expect any issues that
  would postpone the switch till K.
 
  It was mentioned in comments to the spec proposal that there were
  some discussions at the latest summit around possible switch in
  context of Nova that revealed some concerns, though they do not
  seem to be documented anywhere. So if you know anything about it,
  please comment.
 
  So, we'd like to hear from other projects what's your take on that
  move, whether you see any issues or have concerns about it.
 
  Thanks for your comments, /Ihar
 
  [1]: 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Vishvananda Ishaya
I have tried using pymysql in place of mysqldb and in real world concurrency
tests against cinder and nova it performs slower. I was inspired by the mention
of mysql-connector so I just tried that option instead. Mysql-connector seems
to be slightly slower as well, which leads me to believe that the blocking 
inside of
sqlalchemy is not the main bottleneck across projects.

Vish

P.S. The performanace in all cases was abysmal, so performance work definitely
needs to be done, but just the guess that replacing our mysql library is going 
to
solve all of our performance problems appears to be incorrect at first blush.

On Jul 11, 2014, at 10:20 AM, Clark Boylan clark.boy...@gmail.com wrote:

 Before we get too far ahead of ourselves mysql-connector is not hosted
 on pypi. Instead it is an external package link. We recently managed
 to remove all packages that are hosted as external package links from
 openstack and will not add new ones in. Before we can use
 mysql-connector in the gate oracle will need to publish
 mysql-connector on pypi properly.
 
 That said there is at least one other pure python alternative,
 PyMySQL. PyMySQL supports py3k and pypy. We should look at using
 PyMySQL instead if we want to start with a reasonable path to getting
 this in the gate.
 
 Clark
 
 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo
 mangel...@redhat.com wrote:
 +1 here too,
 
 Amazed with the performance gains, x2.4 seems a lot,
 and we'd get rid of deadlocks.
 
 
 
 - Original Message -
 +1
 
 I'm pretty excited about the possibilities here.  I've had this
 mysqldb/eventlet contention in the back of my mind for some time now.
 I'm glad to see some work being done in this area.
 
 Carl
 
 On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka ihrac...@redhat.com 
 wrote:
 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA512
 
 On 09/07/14 13:17, Ihar Hrachyshka wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing other
 threads to eventually unlock the grabbed lock, and instead it just
 blocks the main thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving failing request not
 served. In Nova, there is a special retry mechanism for deadlocks,
 though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not something
 to change in foreseeable future, so we need to find another
 solution that is applicable for Juno. Ideally, the solution should
 be applicable for Icehouse too to allow distributors to resolve
 existing deadlocks without waiting for Juno.
 
 We've had several discussions and attempts to introduce a solution
 to the problem. Thanks to oslo.db guys, we now have more or less
 clear view on the cause of the failures and how to easily fix them.
 The solution is to switch mysqldb to something eventlet aware. The
 best candidate is probably MySQL Connector module that is an
 official MySQL client for Python and that shows some (preliminary)
 good results in terms of performance.
 
 I've made additional testing, creating 2000 networks in parallel (10
 thread workers) for both drivers and comparing results.
 
 With mysqldb: 215.81 sec
 With mysql-connector: 88.66
 
 ~2.4 times performance boost, ok? ;)
 
 I think we should switch to that library *even* if we forget about all
 the nasty deadlocks we experience now.
 
 
 I've posted a Neutron spec for the switch to the new client in Juno
 at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer to
 the new official way to configure services for MySQL. The database
 code won't, ideally, require any major changes, though some
 adaptation for the new client library may be needed. That said,
 Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone or
 Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious wish
 to switch to the new library globally throughout all the projects,
 to reduce devops burden, among other things. My vision is that,
 ideally, we switch all projects to the new library in Juno, though
 we still may leave several projects for K in case any issues arise,
 similar to the way projects switched to 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Carl Baldwin
On Jul 11, 2014 5:32 PM, Vishvananda Ishaya vishvana...@gmail.com wrote:

 I have tried using pymysql in place of mysqldb and in real world
concurrency
 tests against cinder and nova it performs slower. I was inspired by the
mention
 of mysql-connector so I just tried that option instead. Mysql-connector
seems
 to be slightly slower as well, which leads me to believe that the
blocking inside of

Do you have some numbers?  Seems to be slightly slower doesn't really
stand up as an argument against the numbers that have been posted in this
thread.

 sqlalchemy is not the main bottleneck across projects.

 Vish

 P.S. The performanace in all cases was abysmal, so performance work
definitely
 needs to be done, but just the guess that replacing our mysql library is
going to
 solve all of our performance problems appears to be incorrect at first
blush.

The motivation is still mostly deadlock relief but more performance work
should be done.  I agree with you there.  I'm still hopeful for some
improvement from this.


 On Jul 11, 2014, at 10:20 AM, Clark Boylan clark.boy...@gmail.com wrote:

  Before we get too far ahead of ourselves mysql-connector is not hosted
  on pypi. Instead it is an external package link. We recently managed
  to remove all packages that are hosted as external package links from
  openstack and will not add new ones in. Before we can use
  mysql-connector in the gate oracle will need to publish
  mysql-connector on pypi properly.
 
  That said there is at least one other pure python alternative,
  PyMySQL. PyMySQL supports py3k and pypy. We should look at using
  PyMySQL instead if we want to start with a reasonable path to getting
  this in the gate.
 
  Clark
 
  On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo
  mangel...@redhat.com wrote:
  +1 here too,
 
  Amazed with the performance gains, x2.4 seems a lot,
  and we'd get rid of deadlocks.
 
 
 
  - Original Message -
  +1
 
  I'm pretty excited about the possibilities here.  I've had this
  mysqldb/eventlet contention in the back of my mind for some time now.
  I'm glad to see some work being done in this area.
 
  Carl
 
  On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka ihrac...@redhat.com
wrote:
  -BEGIN PGP SIGNED MESSAGE-
  Hash: SHA512
 
  On 09/07/14 13:17, Ihar Hrachyshka wrote:
  Hi all,
 
  Multiple projects are suffering from db lock timeouts due to
  deadlocks deep in mysqldb library that we use to interact with
  mysql servers. In essence, the problem is due to missing eventlet
  support in mysqldb module, meaning when a db lock is encountered,
  the library does not yield to the next green thread, allowing other
  threads to eventually unlock the grabbed lock, and instead it just
  blocks the main thread, that eventually raises timeout exception
  (OperationalError).
 
  The failed operation is not retried, leaving failing request not
  served. In Nova, there is a special retry mechanism for deadlocks,
  though I think it's more a hack than a proper fix.
 
  Neutron is one of the projects that suffer from those timeout
  errors a lot. Partly it's due to lack of discipline in how we do
  nested calls in l3_db and ml2_plugin code, but that's not something
  to change in foreseeable future, so we need to find another
  solution that is applicable for Juno. Ideally, the solution should
  be applicable for Icehouse too to allow distributors to resolve
  existing deadlocks without waiting for Juno.
 
  We've had several discussions and attempts to introduce a solution
  to the problem. Thanks to oslo.db guys, we now have more or less
  clear view on the cause of the failures and how to easily fix them.
  The solution is to switch mysqldb to something eventlet aware. The
  best candidate is probably MySQL Connector module that is an
  official MySQL client for Python and that shows some (preliminary)
  good results in terms of performance.
 
  I've made additional testing, creating 2000 networks in parallel (10
  thread workers) for both drivers and comparing results.
 
  With mysqldb: 215.81 sec
  With mysql-connector: 88.66
 
  ~2.4 times performance boost, ok? ;)
 
  I think we should switch to that library *even* if we forget about
all
  the nasty deadlocks we experience now.
 
 
  I've posted a Neutron spec for the switch to the new client in Juno
  at [1]. Ideally, switch is just a matter of several fixes to
  oslo.db that would enable full support for the new driver already
  supported by SQLAlchemy, plus 'connection' string modified in
  service configuration files, plus documentation updates to refer to
  the new official way to configure services for MySQL. The database
  code won't, ideally, require any major changes, though some
  adaptation for the new client library may be needed. That said,
  Neutron does not seem to require any changes, though it was
  revealed that there are some alembic migration rules in Keystone or
  Glance that need (trivial) modifications.
 
  You can see how 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Carl Baldwin
Clark,

You make a good point.  It's there some resistance to this or is it just a
matter of asking?

Carl
On Jul 11, 2014 12:23 PM, Clark Boylan clark.boy...@gmail.com wrote:

 Before we get too far ahead of ourselves mysql-connector is not hosted
 on pypi. Instead it is an external package link. We recently managed
 to remove all packages that are hosted as external package links from
 openstack and will not add new ones in. Before we can use
 mysql-connector in the gate oracle will need to publish
 mysql-connector on pypi properly.

 That said there is at least one other pure python alternative,
 PyMySQL. PyMySQL supports py3k and pypy. We should look at using
 PyMySQL instead if we want to start with a reasonable path to getting
 this in the gate.

 Clark

 On Fri, Jul 11, 2014 at 10:07 AM, Miguel Angel Ajo Pelayo
 mangel...@redhat.com wrote:
  +1 here too,
 
  Amazed with the performance gains, x2.4 seems a lot,
  and we'd get rid of deadlocks.
 
 
 
  - Original Message -
  +1
 
  I'm pretty excited about the possibilities here.  I've had this
  mysqldb/eventlet contention in the back of my mind for some time now.
  I'm glad to see some work being done in this area.
 
  Carl
 
  On Fri, Jul 11, 2014 at 7:04 AM, Ihar Hrachyshka ihrac...@redhat.com
 wrote:
   -BEGIN PGP SIGNED MESSAGE-
   Hash: SHA512
  
   On 09/07/14 13:17, Ihar Hrachyshka wrote:
   Hi all,
  
   Multiple projects are suffering from db lock timeouts due to
   deadlocks deep in mysqldb library that we use to interact with
   mysql servers. In essence, the problem is due to missing eventlet
   support in mysqldb module, meaning when a db lock is encountered,
   the library does not yield to the next green thread, allowing other
   threads to eventually unlock the grabbed lock, and instead it just
   blocks the main thread, that eventually raises timeout exception
   (OperationalError).
  
   The failed operation is not retried, leaving failing request not
   served. In Nova, there is a special retry mechanism for deadlocks,
   though I think it's more a hack than a proper fix.
  
   Neutron is one of the projects that suffer from those timeout
   errors a lot. Partly it's due to lack of discipline in how we do
   nested calls in l3_db and ml2_plugin code, but that's not something
   to change in foreseeable future, so we need to find another
   solution that is applicable for Juno. Ideally, the solution should
   be applicable for Icehouse too to allow distributors to resolve
   existing deadlocks without waiting for Juno.
  
   We've had several discussions and attempts to introduce a solution
   to the problem. Thanks to oslo.db guys, we now have more or less
   clear view on the cause of the failures and how to easily fix them.
   The solution is to switch mysqldb to something eventlet aware. The
   best candidate is probably MySQL Connector module that is an
   official MySQL client for Python and that shows some (preliminary)
   good results in terms of performance.
  
   I've made additional testing, creating 2000 networks in parallel (10
   thread workers) for both drivers and comparing results.
  
   With mysqldb: 215.81 sec
   With mysql-connector: 88.66
  
   ~2.4 times performance boost, ok? ;)
  
   I think we should switch to that library *even* if we forget about all
   the nasty deadlocks we experience now.
  
  
   I've posted a Neutron spec for the switch to the new client in Juno
   at [1]. Ideally, switch is just a matter of several fixes to
   oslo.db that would enable full support for the new driver already
   supported by SQLAlchemy, plus 'connection' string modified in
   service configuration files, plus documentation updates to refer to
   the new official way to configure services for MySQL. The database
   code won't, ideally, require any major changes, though some
   adaptation for the new client library may be needed. That said,
   Neutron does not seem to require any changes, though it was
   revealed that there are some alembic migration rules in Keystone or
   Glance that need (trivial) modifications.
  
   You can see how trivial the switch can be achieved for a service
   based on example for Neutron [2].
  
   While this is a Neutron specific proposal, there is an obvious wish
   to switch to the new library globally throughout all the projects,
   to reduce devops burden, among other things. My vision is that,
   ideally, we switch all projects to the new library in Juno, though
   we still may leave several projects for K in case any issues arise,
   similar to the way projects switched to oslo.messaging during two
   cycles instead of one. Though looking at how easy Neutron can be
   switched to the new library, I wouldn't expect any issues that
   would postpone the switch till K.
  
   It was mentioned in comments to the spec proposal that there were
   some discussions at the latest summit around possible switch in
   context of Nova that revealed some concerns, though they do 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Jay Pipes

On 07/11/2014 08:04 AM, Ihar Hrachyshka wrote:

-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 09/07/14 13:17, Ihar Hrachyshka wrote:

Hi all,

Multiple projects are suffering from db lock timeouts due to
deadlocks deep in mysqldb library that we use to interact with
mysql servers. In essence, the problem is due to missing eventlet
support in mysqldb module, meaning when a db lock is encountered,
the library does not yield to the next green thread, allowing other
threads to eventually unlock the grabbed lock, and instead it just
blocks the main thread, that eventually raises timeout exception
(OperationalError).

The failed operation is not retried, leaving failing request not
served. In Nova, there is a special retry mechanism for deadlocks,
though I think it's more a hack than a proper fix.

Neutron is one of the projects that suffer from those timeout
errors a lot. Partly it's due to lack of discipline in how we do
nested calls in l3_db and ml2_plugin code, but that's not something
to change in foreseeable future, so we need to find another
solution that is applicable for Juno. Ideally, the solution should
be applicable for Icehouse too to allow distributors to resolve
existing deadlocks without waiting for Juno.

We've had several discussions and attempts to introduce a solution
to the problem. Thanks to oslo.db guys, we now have more or less
clear view on the cause of the failures and how to easily fix them.
The solution is to switch mysqldb to something eventlet aware. The
best candidate is probably MySQL Connector module that is an
official MySQL client for Python and that shows some (preliminary)
good results in terms of performance.


I've made additional testing, creating 2000 networks in parallel (10
thread workers) for both drivers and comparing results.

With mysqldb: 215.81 sec
With mysql-connector: 88.66

~2.4 times performance boost, ok? ;)


That really doesn't tell me much.

Please remember that performance != scalability.

If you showed the test/benchmark code, that would be great. You need to 
run your benchmarks at varying levels of concurrency and varying levels 
of read/write ratios for the workers. Otherwise it's like looking at a a 
single dot of paint on a painting. Without looking at the patterns of 
throughput (performance) and concurrency/locking (scalability) with 
various levels of workers and read/write ratios, you miss the whole picture.


Another thing to ensure is that you are using real *processes*, not 
threads, so that you actually simulate a real OpenStack service like 
Nova or Neutron, which are multi-plexed, not multi-threaded, and have a 
greenlet pool within each worker process.


Best
-jay


I think we should switch to that library *even* if we forget about all
the nasty deadlocks we experience now.



I've posted a Neutron spec for the switch to the new client in Juno
at [1]. Ideally, switch is just a matter of several fixes to
oslo.db that would enable full support for the new driver already
supported by SQLAlchemy, plus 'connection' string modified in
service configuration files, plus documentation updates to refer to
the new official way to configure services for MySQL. The database
code won't, ideally, require any major changes, though some
adaptation for the new client library may be needed. That said,
Neutron does not seem to require any changes, though it was
revealed that there are some alembic migration rules in Keystone or
Glance that need (trivial) modifications.

You can see how trivial the switch can be achieved for a service
based on example for Neutron [2].

While this is a Neutron specific proposal, there is an obvious wish
to switch to the new library globally throughout all the projects,
to reduce devops burden, among other things. My vision is that,
ideally, we switch all projects to the new library in Juno, though
we still may leave several projects for K in case any issues arise,
similar to the way projects switched to oslo.messaging during two
cycles instead of one. Though looking at how easy Neutron can be
switched to the new library, I wouldn't expect any issues that
would postpone the switch till K.

It was mentioned in comments to the spec proposal that there were
some discussions at the latest summit around possible switch in
context of Nova that revealed some concerns, though they do not
seem to be documented anywhere. So if you know anything about it,
please comment.

So, we'd like to hear from other projects what's your take on that
move, whether you see any issues or have concerns about it.

Thanks for your comments, /Ihar

[1]: https://review.openstack.org/#/c/104905/ [2]:
https://review.openstack.org/#/c/105209/

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Mike Bayer

On 7/11/14, 7:26 PM, Carl Baldwin wrote:


 On Jul 11, 2014 5:32 PM, Vishvananda Ishaya vishvana...@gmail.com
mailto:vishvana...@gmail.com wrote:
 
  I have tried using pymysql in place of mysqldb and in real world
concurrency
  tests against cinder and nova it performs slower. I was inspired by
the mention
  of mysql-connector so I just tried that option instead.
Mysql-connector seems
  to be slightly slower as well, which leads me to believe that the
blocking inside of

 Do you have some numbers?  Seems to be slightly slower doesn't
really stand up as an argument against the numbers that have been posted
in this thread.

  sqlalchemy is not the main bottleneck across projects.
 
  Vish
 
  P.S. The performanace in all cases was abysmal, so performance work
definitely
  needs to be done, but just the guess that replacing our mysql
library is going to
  solve all of our performance problems appears to be incorrect at
first blush.

 The motivation is still mostly deadlock relief but more performance
work should be done.  I agree with you there.  I'm still hopeful for
some improvement from this.


To identify performance that's alleviated by async you have to establish
up front that IO blocking is the issue, which would entail having code
that's blazing fast until you start running it against concurrent
connections, at which point you can identify via profiling that IO
operations are being serialized.   This is a very specific issue.

In contrast, to identify why some arbitrary openstack app is slow, my
bet is that async is often not the big issue.   Every day I look at
openstack code and talk to people working on things,  I see many
performance issues that have nothing to do with concurrency, and as I
detailed in my wiki page at
https://wiki.openstack.org/wiki/OpenStack_and_SQLAlchemy there is a long
road to cleaning up all the excessive queries, hundreds of unnecessary
rows and columns being pulled over the network, unindexed lookups,
subquery joins, hammering of Python-intensive operations (often due to
the nature of OS apps as lots and lots of tiny API calls) that can be
cached.   There's a clear path to tons better performance documented
there and most of it is not about async  - which means that successful
async isn't going to solve all those issues.

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Jay Pipes

On 07/11/2014 09:17 PM, Mike Bayer wrote:
...

To identify performance that's alleviated by async you have to
establish up front that IO blocking is the issue, which would entail
having code that's blazing fast until you start running it against
concurrent connections, at which point you can identify via profiling
that IO operations are being serialized.   This is a very specific
issue.

In contrast, to identify why some arbitrary openstack app is slow, my
 bet is that async is often not the big issue.   Every day I look at
 openstack code and talk to people working on things,  I see many
performance issues that have nothing to do with concurrency, and as I
 detailed in my wiki page at
https://wiki.openstack.org/wiki/OpenStack_and_SQLAlchemy there is a
long road to cleaning up all the excessive queries, hundreds of
unnecessary rows and columns being pulled over the network, unindexed
lookups, subquery joins, hammering of Python-intensive operations
(often due to the nature of OS apps as lots and lots of tiny API
calls) that can be cached.   There's a clear path to tons better
performance documented there and most of it is not about async  -
which means that successful async isn't going to solve all those
issues.


Yep, couldn't agree more.

Frankly, the steps you outline in the wiki above are excellent examples 
of where we can make significant gains in both performance and 
scalability. In addition to those you listed, the underlying database 
schemas themselves, with the excessive use of large VARCHAR fields, BLOB 
fields for JSONified values, and the general bad strategy of bunching 
heavily-read fields with infrequently-read fields in the same tables, 
are also a source of poor overall database performance.


Best,
-jay

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-11 Thread Mike Bayer

On 7/11/14, 11:26 PM, Jay Pipes wrote:
 Yep, couldn't agree more.

 Frankly, the steps you outline in the wiki above are excellent
 examples of where we can make significant gains in both performance
 and scalability. In addition to those you listed, the underlying
 database schemas themselves, with the excessive use of large VARCHAR
 fields, BLOB fields for JSONified values, and the general bad strategy
 of bunching heavily-read fields with infrequently-read fields in the
 same tables, are also a source of poor overall database performance.
Well the topic of schema modifications I actually left out of that
document entirely for starters - I made a conscious choice to focus
entirely on things that don't involve any apps changing any of their
fundamental approaches or schemas...at least just yet! :)I'm hoping
that as oslo.db improves and the patterns start to roll out, we can
start working on schema design too.Because yeah I've seen the giant
lists of VARCHAR everything and just said, OK well we're going to have
to get to that..just not right now :).



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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-10 Thread Angus Lees
On 10 July 2014 00:59, Roman Podoliaka rpodoly...@mirantis.com wrote:

 Not sure what issues you are talking about, but I just replaced
 mysql with mysql+mysqlconnector in my db connection string  in
 neutron.conf and neutron-db-manage upgrade head worked like a charm
 for an empty schema.


Yep, I don't think we're far away from it being that simple.  Most of the
changes/work I've seen discussed is in shifting the test environments and
suitably addressing everyone's performance/uncertainty concerns.

Ihar, could please elaborate on what changes to oslo.db are needed?
 (as an oslo.db developer I'm very interested in this part :) )


The changes I've been working on are (and most of these need oslo.db
reviews):

https://review.openstack.org/#/c/104436/
Test that concurrent sqlalchemy transactions don't block
(This test reproduces the core issue.  There's an open question where it
belongs)

https://review.openstack.org/#/c/104425/
Add DBDuplicateEntry detection for mysqlconnector driver

https://review.openstack.org/#/c/104428/
Allow tox tests with complex OS_TEST_DBAPI_CONNECTION URLs

https://review.openstack.org/#/c/104447/
Support OS_TEST_DBAPI_ADMIN_CONNECTION override

https://review.openstack.org/#/c/104430/
Don't drop pre-existing database before tests

https://github.com/zzzeek/sqlalchemy/pull/102
sqlalchemy mysql unicode improvement, that has various workarounds
available to us in the meantime

 - Gus
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-10 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 10/07/14 08:09, Angus Lees wrote:
 On 10 July 2014 00:59, Roman Podoliaka rpodoly...@mirantis.com
 wrote:
 
 Not sure what issues you are talking about, but I just replaced 
 mysql with mysql+mysqlconnector in my db connection string
 in neutron.conf and neutron-db-manage upgrade head worked like
 a charm for an empty schema.
 
 
 Yep, I don't think we're far away from it being that simple.  Most
 of the changes/work I've seen discussed is in shifting the test
 environments and suitably addressing everyone's
 performance/uncertainty concerns.
 
 Ihar, could please elaborate on what changes to oslo.db are
 needed?

AFAIK we should:
- - set raise_on_warnings to False for sqlconnector (the current default
for sqlalchemy is True, which is wrong and to be fixed, but will need
to wait for the next release which is months away from us);
- - set encoding=utf8 until sqalchemy 1.0 is released and we require it.

Plus changes you already track (duplicate error detection and testing
parity - the latter is probably not a requirement).

 (as an oslo.db developer I'm very interested in this part :) )
 
 
 The changes I've been working on are (and most of these need
 oslo.db reviews):
 
 https://review.openstack.org/#/c/104436/ Test that concurrent
 sqlalchemy transactions don't block (This test reproduces the core
 issue.  There's an open question where it belongs)
 
 https://review.openstack.org/#/c/104425/ Add DBDuplicateEntry
 detection for mysqlconnector driver
 
 https://review.openstack.org/#/c/104428/ Allow tox tests with
 complex OS_TEST_DBAPI_CONNECTION URLs
 
 https://review.openstack.org/#/c/104447/ Support
 OS_TEST_DBAPI_ADMIN_CONNECTION override
 
 https://review.openstack.org/#/c/104430/ Don't drop pre-existing
 database before tests
 
 https://github.com/zzzeek/sqlalchemy/pull/102 sqlalchemy mysql
 unicode improvement, that has various workarounds available to us
 in the meantime
 
 - Gus
 
 
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-09 Thread Roman Podoliaka
Hi Ihar,

AFAIU, the switch is a matter of pip install + specifying the correct
db URI in the config files. I'm not sure why you are filing a spec in
Neutron project. IMHO, this has nothing to do with projects, but
rather a purely deployment question. E.g. don't we have
PostgreSQL+psycopg2 or MySQL+pymysql deployments of OpenStack right
now?

I think what you really want is to change the defaults we test in the
gate, which is a different problem.

Thanks,
Roman

On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka ihrac...@redhat.com wrote:
 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA512

 Hi all,

 Multiple projects are suffering from db lock timeouts due to deadlocks
 deep in mysqldb library that we use to interact with mysql servers. In
 essence, the problem is due to missing eventlet support in mysqldb
 module, meaning when a db lock is encountered, the library does not
 yield to the next green thread, allowing other threads to eventually
 unlock the grabbed lock, and instead it just blocks the main thread,
 that eventually raises timeout exception (OperationalError).

 The failed operation is not retried, leaving failing request not
 served. In Nova, there is a special retry mechanism for deadlocks,
 though I think it's more a hack than a proper fix.

 Neutron is one of the projects that suffer from those timeout errors a
 lot. Partly it's due to lack of discipline in how we do nested calls
 in l3_db and ml2_plugin code, but that's not something to change in
 foreseeable future, so we need to find another solution that is
 applicable for Juno. Ideally, the solution should be applicable for
 Icehouse too to allow distributors to resolve existing deadlocks
 without waiting for Juno.

 We've had several discussions and attempts to introduce a solution to
 the problem. Thanks to oslo.db guys, we now have more or less clear
 view on the cause of the failures and how to easily fix them. The
 solution is to switch mysqldb to something eventlet aware. The best
 candidate is probably MySQL Connector module that is an official MySQL
 client for Python and that shows some (preliminary) good results in
 terms of performance.

 I've posted a Neutron spec for the switch to the new client in Juno at
 [1]. Ideally, switch is just a matter of several fixes to oslo.db that
 would enable full support for the new driver already supported by
 SQLAlchemy, plus 'connection' string modified in service configuration
 files, plus documentation updates to refer to the new official way to
 configure services for MySQL. The database code won't, ideally,
 require any major changes, though some adaptation for the new client
 library may be needed. That said, Neutron does not seem to require any
 changes, though it was revealed that there are some alembic migration
 rules in Keystone or Glance that need (trivial) modifications.

 You can see how trivial the switch can be achieved for a service based
 on example for Neutron [2].

 While this is a Neutron specific proposal, there is an obvious wish to
 switch to the new library globally throughout all the projects, to
 reduce devops burden, among other things. My vision is that, ideally,
 we switch all projects to the new library in Juno, though we still may
 leave several projects for K in case any issues arise, similar to the
 way projects switched to oslo.messaging during two cycles instead of
 one. Though looking at how easy Neutron can be switched to the new
 library, I wouldn't expect any issues that would postpone the switch
 till K.

 It was mentioned in comments to the spec proposal that there were some
 discussions at the latest summit around possible switch in context of
 Nova that revealed some concerns, though they do not seem to be
 documented anywhere. So if you know anything about it, please comment.

 So, we'd like to hear from other projects what's your take on that
 move, whether you see any issues or have concerns about it.

 Thanks for your comments,
 /Ihar

 [1]: https://review.openstack.org/#/c/104905/
 [2]: https://review.openstack.org/#/c/105209/
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-09 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 09/07/14 15:00, Roman Podoliaka wrote:
 Hi Ihar,
 
 AFAIU, the switch is a matter of pip install + specifying the
 correct db URI in the config files. I'm not sure why you are filing
 a spec in Neutron project. IMHO, this has nothing to do with
 projects, but rather a purely deployment question. E.g. don't we
 have PostgreSQL+psycopg2 or MySQL+pymysql deployments of OpenStack
 right now?

The issue was raised in Neutron because it suffers a lot from those
deadlocks, and because initially I saw the switch as local to this
specific project, that would lead other projects by example and not as
an enforced rule. I would be glad to put the spec in some other,
better place. Do you know any?

I don't know whether we have other MySQL deployments not using
MySQLdb; if so, they are not configured as per official documentation.

See:
- -
http://docs.openstack.org/icehouse/install-guide/install/yum/content/basics-database-controller.html
- -
http://docs.openstack.org/icehouse/install-guide/install/yum/content/basics-database-node.html
- -
http://docs.openstack.org/icehouse/install-guide/install/yum/content/neutron-ml2-controller-node.html

If we want people to use a new module, we need to update the docs not
to refer to MySQLdb. Or at least inform them that deadlocks may occur
when using the library [and I think this is enough to just remove any
references to the library from the documentation.]

 
 I think what you really want is to change the defaults we test in
 the gate, which is a different problem.

It's lots of different things to do:

- - some work to be tracked in oslo.db (and old db code from incubator?);
- - update neutron code if needed (though preliminary testing didn't
reveal any specific changes for this specific project though, while
others may need trivial updates);
- - switch defaults in devstack;
- - update documentation to refer to the new library.

 
 Thanks, Roman
 
 On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka
 ihrac...@redhat.com wrote: Hi all,
 
 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing other
 threads to eventually unlock the grabbed lock, and instead it just
 blocks the main thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving failing request not 
 served. In Nova, there is a special retry mechanism for deadlocks, 
 though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not something
 to change in foreseeable future, so we need to find another
 solution that is applicable for Juno. Ideally, the solution should
 be applicable for Icehouse too to allow distributors to resolve
 existing deadlocks without waiting for Juno.
 
 We've had several discussions and attempts to introduce a solution
 to the problem. Thanks to oslo.db guys, we now have more or less
 clear view on the cause of the failures and how to easily fix them.
 The solution is to switch mysqldb to something eventlet aware. The
 best candidate is probably MySQL Connector module that is an
 official MySQL client for Python and that shows some (preliminary)
 good results in terms of performance.
 
 I've posted a Neutron spec for the switch to the new client in Juno
 at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer to
 the new official way to configure services for MySQL. The database
 code won't, ideally, require any major changes, though some
 adaptation for the new client library may be needed. That said,
 Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone or
 Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious wish
 to switch to the new library globally throughout all the projects,
 to reduce devops burden, among other things. My vision is that,
 ideally, we switch all projects to the new library in Juno, though
 we still may leave several projects for K in case any issues arise,
 similar to the way projects switched to oslo.messaging during two
 cycles instead of one. Though looking at how easy Neutron can be
 switched to the new library, I wouldn't expect any issues that
 would postpone the switch till K.
 
 It was mentioned 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-09 Thread Sean Dague
On 07/09/2014 09:00 AM, Roman Podoliaka wrote:
 Hi Ihar,
 
 AFAIU, the switch is a matter of pip install + specifying the correct
 db URI in the config files. I'm not sure why you are filing a spec in
 Neutron project. IMHO, this has nothing to do with projects, but
 rather a purely deployment question. E.g. don't we have
 PostgreSQL+psycopg2 or MySQL+pymysql deployments of OpenStack right
 now?
 
 I think what you really want is to change the defaults we test in the
 gate, which is a different problem.

Because this is really a *new* driver. As you can see by the attempted
run, it doesn't work with alembic given the definitions that neutron
has. So it's not like this is currently compatible with OpenStack code.

 
 Thanks,
 Roman
 
 On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka ihrac...@redhat.com wrote:
 Hi all,
 
 Multiple projects are suffering from db lock timeouts due to deadlocks
 deep in mysqldb library that we use to interact with mysql servers. In
 essence, the problem is due to missing eventlet support in mysqldb
 module, meaning when a db lock is encountered, the library does not
 yield to the next green thread, allowing other threads to eventually
 unlock the grabbed lock, and instead it just blocks the main thread,
 that eventually raises timeout exception (OperationalError).
 
 The failed operation is not retried, leaving failing request not
 served. In Nova, there is a special retry mechanism for deadlocks,
 though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout errors a
 lot. Partly it's due to lack of discipline in how we do nested calls
 in l3_db and ml2_plugin code, but that's not something to change in
 foreseeable future, so we need to find another solution that is
 applicable for Juno. Ideally, the solution should be applicable for
 Icehouse too to allow distributors to resolve existing deadlocks
 without waiting for Juno.
 
 We've had several discussions and attempts to introduce a solution to
 the problem. Thanks to oslo.db guys, we now have more or less clear
 view on the cause of the failures and how to easily fix them. The
 solution is to switch mysqldb to something eventlet aware. The best
 candidate is probably MySQL Connector module that is an official MySQL
 client for Python and that shows some (preliminary) good results in
 terms of performance.
 
 I've posted a Neutron spec for the switch to the new client in Juno at
 [1]. Ideally, switch is just a matter of several fixes to oslo.db that
 would enable full support for the new driver already supported by
 SQLAlchemy, plus 'connection' string modified in service configuration
 files, plus documentation updates to refer to the new official way to
 configure services for MySQL. The database code won't, ideally,
 require any major changes, though some adaptation for the new client
 library may be needed. That said, Neutron does not seem to require any
 changes, though it was revealed that there are some alembic migration
 rules in Keystone or Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service based
 on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious wish to
 switch to the new library globally throughout all the projects, to
 reduce devops burden, among other things. My vision is that, ideally,
 we switch all projects to the new library in Juno, though we still may
 leave several projects for K in case any issues arise, similar to the
 way projects switched to oslo.messaging during two cycles instead of
 one. Though looking at how easy Neutron can be switched to the new
 library, I wouldn't expect any issues that would postpone the switch
 till K.
 
 It was mentioned in comments to the spec proposal that there were some
 discussions at the latest summit around possible switch in context of
 Nova that revealed some concerns, though they do not seem to be
 documented anywhere. So if you know anything about it, please comment.
 
 So, we'd like to hear from other projects what's your take on that
 move, whether you see any issues or have concerns about it.
 
 Thanks for your comments,
 /Ihar
 
 [1]: https://review.openstack.org/#/c/104905/
 [2]: https://review.openstack.org/#/c/105209/

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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-09 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 09/07/14 15:40, Sean Dague wrote:
 On 07/09/2014 09:00 AM, Roman Podoliaka wrote:
 Hi Ihar,
 
 AFAIU, the switch is a matter of pip install + specifying the
 correct db URI in the config files. I'm not sure why you are
 filing a spec in Neutron project. IMHO, this has nothing to do
 with projects, but rather a purely deployment question. E.g.
 don't we have PostgreSQL+psycopg2 or MySQL+pymysql deployments of
 OpenStack right now?
 
 I think what you really want is to change the defaults we test in
 the gate, which is a different problem.
 
 Because this is really a *new* driver. As you can see by the
 attempted run, it doesn't work with alembic given the definitions
 that neutron has. So it's not like this is currently compatible
 with OpenStack code.

Well, to fix that, you just need to specify raise_on_warnings=False
for connection (it's default for mysqldb but not mysql-connector).
I've done it in devstack patch for now, but probably it belongs to
oslo.db.

 
 
 Thanks, Roman
 
 On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka
 ihrac...@redhat.com wrote: Hi all,
 
 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing
 other threads to eventually unlock the grabbed lock, and instead
 it just blocks the main thread, that eventually raises timeout
 exception (OperationalError).
 
 The failed operation is not retried, leaving failing request not 
 served. In Nova, there is a special retry mechanism for
 deadlocks, though I think it's more a hack than a proper fix.
 
 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not
 something to change in foreseeable future, so we need to find
 another solution that is applicable for Juno. Ideally, the
 solution should be applicable for Icehouse too to allow
 distributors to resolve existing deadlocks without waiting for
 Juno.
 
 We've had several discussions and attempts to introduce a
 solution to the problem. Thanks to oslo.db guys, we now have more
 or less clear view on the cause of the failures and how to easily
 fix them. The solution is to switch mysqldb to something eventlet
 aware. The best candidate is probably MySQL Connector module that
 is an official MySQL client for Python and that shows some
 (preliminary) good results in terms of performance.
 
 I've posted a Neutron spec for the switch to the new client in
 Juno at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer
 to the new official way to configure services for MySQL. The
 database code won't, ideally, require any major changes, though
 some adaptation for the new client library may be needed. That
 said, Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone
 or Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an obvious
 wish to switch to the new library globally throughout all the
 projects, to reduce devops burden, among other things. My vision
 is that, ideally, we switch all projects to the new library in
 Juno, though we still may leave several projects for K in case
 any issues arise, similar to the way projects switched to
 oslo.messaging during two cycles instead of one. Though looking
 at how easy Neutron can be switched to the new library, I
 wouldn't expect any issues that would postpone the switch till
 K.
 
 It was mentioned in comments to the spec proposal that there were
 some discussions at the latest summit around possible switch in
 context of Nova that revealed some concerns, though they do not
 seem to be documented anywhere. So if you know anything about it,
 please comment.
 
 So, we'd like to hear from other projects what's your take on
 that move, whether you see any issues or have concerns about it.
 
 Thanks for your comments, /Ihar
 
 [1]: https://review.openstack.org/#/c/104905/ [2]:
 https://review.openstack.org/#/c/105209/
 
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Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-09 Thread Roman Podoliaka
Hi all,

Not sure what issues you are talking about, but I just replaced
mysql with mysql+mysqlconnector in my db connection string  in
neutron.conf and neutron-db-manage upgrade head worked like a charm
for an empty schema.

Ihar, could please elaborate on what changes to oslo.db are needed?
(as an oslo.db developer I'm very interested in this part :) )

Thanks,
Roman

On Wed, Jul 9, 2014 at 5:43 PM, Ihar Hrachyshka ihrac...@redhat.com wrote:
 -BEGIN PGP SIGNED MESSAGE-
 Hash: SHA512

 On 09/07/14 15:40, Sean Dague wrote:
 On 07/09/2014 09:00 AM, Roman Podoliaka wrote:
 Hi Ihar,

 AFAIU, the switch is a matter of pip install + specifying the
 correct db URI in the config files. I'm not sure why you are
 filing a spec in Neutron project. IMHO, this has nothing to do
 with projects, but rather a purely deployment question. E.g.
 don't we have PostgreSQL+psycopg2 or MySQL+pymysql deployments of
 OpenStack right now?

 I think what you really want is to change the defaults we test in
 the gate, which is a different problem.

 Because this is really a *new* driver. As you can see by the
 attempted run, it doesn't work with alembic given the definitions
 that neutron has. So it's not like this is currently compatible
 with OpenStack code.

 Well, to fix that, you just need to specify raise_on_warnings=False
 for connection (it's default for mysqldb but not mysql-connector).
 I've done it in devstack patch for now, but probably it belongs to
 oslo.db.



 Thanks, Roman

 On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka
 ihrac...@redhat.com wrote: Hi all,

 Multiple projects are suffering from db lock timeouts due to
 deadlocks deep in mysqldb library that we use to interact with
 mysql servers. In essence, the problem is due to missing eventlet
 support in mysqldb module, meaning when a db lock is encountered,
 the library does not yield to the next green thread, allowing
 other threads to eventually unlock the grabbed lock, and instead
 it just blocks the main thread, that eventually raises timeout
 exception (OperationalError).

 The failed operation is not retried, leaving failing request not
 served. In Nova, there is a special retry mechanism for
 deadlocks, though I think it's more a hack than a proper fix.

 Neutron is one of the projects that suffer from those timeout
 errors a lot. Partly it's due to lack of discipline in how we do
 nested calls in l3_db and ml2_plugin code, but that's not
 something to change in foreseeable future, so we need to find
 another solution that is applicable for Juno. Ideally, the
 solution should be applicable for Icehouse too to allow
 distributors to resolve existing deadlocks without waiting for
 Juno.

 We've had several discussions and attempts to introduce a
 solution to the problem. Thanks to oslo.db guys, we now have more
 or less clear view on the cause of the failures and how to easily
 fix them. The solution is to switch mysqldb to something eventlet
 aware. The best candidate is probably MySQL Connector module that
 is an official MySQL client for Python and that shows some
 (preliminary) good results in terms of performance.

 I've posted a Neutron spec for the switch to the new client in
 Juno at [1]. Ideally, switch is just a matter of several fixes to
 oslo.db that would enable full support for the new driver already
 supported by SQLAlchemy, plus 'connection' string modified in
 service configuration files, plus documentation updates to refer
 to the new official way to configure services for MySQL. The
 database code won't, ideally, require any major changes, though
 some adaptation for the new client library may be needed. That
 said, Neutron does not seem to require any changes, though it was
 revealed that there are some alembic migration rules in Keystone
 or Glance that need (trivial) modifications.

 You can see how trivial the switch can be achieved for a service
 based on example for Neutron [2].

 While this is a Neutron specific proposal, there is an obvious
 wish to switch to the new library globally throughout all the
 projects, to reduce devops burden, among other things. My vision
 is that, ideally, we switch all projects to the new library in
 Juno, though we still may leave several projects for K in case
 any issues arise, similar to the way projects switched to
 oslo.messaging during two cycles instead of one. Though looking
 at how easy Neutron can be switched to the new library, I
 wouldn't expect any issues that would postpone the switch till
 K.

 It was mentioned in comments to the spec proposal that there were
 some discussions at the latest summit around possible switch in
 context of Nova that revealed some concerns, though they do not
 seem to be documented anywhere. So if you know anything about it,
 please comment.

 So, we'd like to hear from other projects what's your take on
 that move, whether you see any issues or have concerns about it.

 Thanks for your comments, /Ihar

 [1]: 

Re: [openstack-dev] [neutron][all] switch from mysqldb to another eventlet aware mysql client

2014-07-09 Thread Ihar Hrachyshka
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA512

On 09/07/14 16:59, Roman Podoliaka wrote:
 Hi all,
 
 Not sure what issues you are talking about, but I just replaced 
 mysql with mysql+mysqlconnector in my db connection string  in 
 neutron.conf and neutron-db-manage upgrade head worked like a
 charm for an empty schema.

Have you enabled metering plugin as devstack in gate does? That's what
fails. If it's not enabled, everything succeeds, as you've mentioned.
If it's enabled, sqlconnector driver raise error on warning due to
'CREATE TABLE IF NOT EXISTS' statement is used. The statement raises
warning because some backends do not support it. Though I don't think
there's a way to rewrite the migration rule without using the
statement: using alembic.op.create_table does not generate IF NOT
EXISTS, and we need it for offline migration where we can't check
table presence in runtime.

 
 Ihar, could please elaborate on what changes to oslo.db are
 needed? (as an oslo.db developer I'm very interested in this part
 :) )

You can find some patches at Angus dashboard [1]. As for the change I
refer to, we need to set raise_on_warnings for mysqlconnector dialect
in create_engine().

[1]:
https://review.openstack.org/#/q/owner:%22Angus+Lees+%253Cgus%2540inodes.org%253E%22+status:open,n,z

 
 Thanks, Roman
 
 On Wed, Jul 9, 2014 at 5:43 PM, Ihar Hrachyshka
 ihrac...@redhat.com wrote: On 09/07/14 15:40, Sean Dague wrote:
 On 07/09/2014 09:00 AM, Roman Podoliaka wrote:
 Hi Ihar,
 
 AFAIU, the switch is a matter of pip install + specifying
 the correct db URI in the config files. I'm not sure why
 you are filing a spec in Neutron project. IMHO, this has
 nothing to do with projects, but rather a purely deployment
 question. E.g. don't we have PostgreSQL+psycopg2 or
 MySQL+pymysql deployments of OpenStack right now?
 
 I think what you really want is to change the defaults we
 test in the gate, which is a different problem.
 
 Because this is really a *new* driver. As you can see by the 
 attempted run, it doesn't work with alembic given the
 definitions that neutron has. So it's not like this is
 currently compatible with OpenStack code.
 
 Well, to fix that, you just need to specify
 raise_on_warnings=False for connection (it's default for mysqldb
 but not mysql-connector). I've done it in devstack patch for now,
 but probably it belongs to oslo.db.
 
 
 
 Thanks, Roman
 
 On Wed, Jul 9, 2014 at 2:17 PM, Ihar Hrachyshka 
 ihrac...@redhat.com wrote: Hi all,
 
 Multiple projects are suffering from db lock timeouts due
 to deadlocks deep in mysqldb library that we use to
 interact with mysql servers. In essence, the problem is due
 to missing eventlet support in mysqldb module, meaning when
 a db lock is encountered, the library does not yield to the
 next green thread, allowing other threads to eventually
 unlock the grabbed lock, and instead it just blocks the
 main thread, that eventually raises timeout exception
 (OperationalError).
 
 The failed operation is not retried, leaving failing
 request not served. In Nova, there is a special retry
 mechanism for deadlocks, though I think it's more a hack
 than a proper fix.
 
 Neutron is one of the projects that suffer from those
 timeout errors a lot. Partly it's due to lack of discipline
 in how we do nested calls in l3_db and ml2_plugin code, but
 that's not something to change in foreseeable future, so we
 need to find another solution that is applicable for Juno.
 Ideally, the solution should be applicable for Icehouse too
 to allow distributors to resolve existing deadlocks without
 waiting for Juno.
 
 We've had several discussions and attempts to introduce a 
 solution to the problem. Thanks to oslo.db guys, we now
 have more or less clear view on the cause of the failures
 and how to easily fix them. The solution is to switch
 mysqldb to something eventlet aware. The best candidate is
 probably MySQL Connector module that is an official MySQL
 client for Python and that shows some (preliminary) good
 results in terms of performance.
 
 I've posted a Neutron spec for the switch to the new client
 in Juno at [1]. Ideally, switch is just a matter of several
 fixes to oslo.db that would enable full support for the new
 driver already supported by SQLAlchemy, plus 'connection'
 string modified in service configuration files, plus
 documentation updates to refer to the new official way to
 configure services for MySQL. The database code won't,
 ideally, require any major changes, though some adaptation
 for the new client library may be needed. That said,
 Neutron does not seem to require any changes, though it
 was revealed that there are some alembic migration rules in
 Keystone or Glance that need (trivial) modifications.
 
 You can see how trivial the switch can be achieved for a
 service based on example for Neutron [2].
 
 While this is a Neutron specific proposal, there is an
 obvious wish to switch to the new library globally
 throughout all the projects, to