Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
c.execute(self)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/unitofwork.py",
> line 475, in execute
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers uow
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/persistence.py",
> line 64, in save_obj
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers table,
> insert)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/persistence.py",
> line 530, in _emit_insert_statements
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> execute(statement, multiparams)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
> line 1449, in execute
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers params)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
> line 1584, in _execute_clauseelement
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> compiled_sql, distilled_params
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
> line 1698, in _execute_context
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> context)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
> line 1691, in _execute_context
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> context)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/default.py",
> line 331, in do_execute
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> cursor.execute(statement, parameters)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/MySQLdb/cursors.py", line 173, in
> execute
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> self.errorhandler(self, exc, value)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/MySQLdb/connections.py", line 36, in
> defaulterrorhandler
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers raise
> errorclass, errorvalue
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> OperationalError: (OperationalError) (1205, 'Lock wait timeout exceeded;
> try restarting transaction') 'INSERT INTO ml2_port_bindings (port_id, host,
> vnic_type, profile, vif_type, vif_details, driver, segment) VALUES (%s, %s,
> %s, %s, %s, %s, %s, %s)' ('2f7996c2-7a60-4334-a71d-11e82285e272', '',
> 'normal', "{'type': 1, 'priority': 2}", 'unbound', '', None, None)
>
>
> Thanks,
> Li Ma
>
>
> - Original Message -
> From: "Kevin Benton"
> To: "OpenStack Development Mailing List (not for usage questions)" <
> openstack-dev@lists.openstack.org>
> Sent: 星期四, 2014年 6 月 26日 上午 10:32:47
> Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when
> developing new mechanism driver
>
>
>
> What is in the variable named 'query' that you are trying to merge into
> the session? Can you include the full create_port_postcommit method? The
> line raising the exception ends with " {'port_id': port_id})" and that
> doesn't matching anything included in your sample.
>
>
>
> On Wed, Jun 25, 2014 at 6:53 PM, Li Ma < skywalker.n...@gmail.com > wrote:
>
>
> Here's a code sample which can raise db lock wait exception:
>
> def create_port_postcommit(self, context):
>
> port_id = ...
> with session.begin(subtransactions=True):
> try:
> binding = (session.query(models.PortBinding).
> filter(models.PortBinding.port_id.startswith(port_id)).
> one())
> # Here I modify some attributes if port binding is existed
> session.merge(query)
&g
Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
CE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/persistence.py",
line 530, in _emit_insert_statements
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
execute(statement, multiparams)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
line 1449, in execute
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers params)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
line 1584, in _execute_clauseelement
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
compiled_sql, distilled_params
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
line 1698, in _execute_context
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers context)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/base.py",
line 1691, in _execute_context
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers context)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/engine/default.py",
line 331, in do_execute
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
cursor.execute(statement, parameters)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/MySQLdb/cursors.py", line 173, in execute
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
self.errorhandler(self, exc, value)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/MySQLdb/connections.py", line 36, in
defaulterrorhandler
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers raise
errorclass, errorvalue
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
OperationalError: (OperationalError) (1205, 'Lock wait timeout exceeded; try
restarting transaction') 'INSERT INTO ml2_port_bindings (port_id, host,
vnic_type, profile, vif_type, vif_details, driver, segment) VALUES (%s, %s, %s,
%s, %s, %s, %s, %s)' ('2f7996c2-7a60-4334-a71d-11e82285e272', '', 'normal',
"{'type': 1, 'priority': 2}", 'unbound', '', None, None)
Thanks,
Li Ma
- Original Message -
From: "Kevin Benton"
To: "OpenStack Development Mailing List (not for usage questions)"
Sent: 星期四, 2014年 6 月 26日 上午 10:32:47
Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing
new mechanism driver
What is in the variable named 'query' that you are trying to merge into the
session? Can you include the full create_port_postcommit method? The line
raising the exception ends with " {'port_id': port_id})" and that doesn't
matching anything included in your sample.
On Wed, Jun 25, 2014 at 6:53 PM, Li Ma < skywalker.n...@gmail.com > wrote:
Here's a code sample which can raise db lock wait exception:
def create_port_postcommit(self, context):
port_id = ...
with session.begin(subtransactions=True):
try:
binding = (session.query(models.PortBinding).
filter(models.PortBinding.port_id.startswith(port_id)).
one())
# Here I modify some attributes if port binding is existed
session.merge(query)
except exc.NoResultFound:
# Here I insert new port binding record to initialize some attributes
except ...
LOG.error("error happened")
The exception is as follows:
2014-06-25 10:05:17.195 9915 ERROR neutron.plugins.ml2.managers
[req-961680da-ce69-43c6-974c-57132def411d None] Mechanism driver 'hello' failed
in create_port_postcommit
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers Traceback (most
recent call last):
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib/python2.6/site-packages/neutron/plugins/ml2/managers.py", line 158,
in _call_on_drivers
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
getattr(driver.obj, method_name)(context)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib/python2.6/site-packages/neutron/plugins/ml2/drivers/mech_hello.py",
line 95, in create_port_postcommit
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers {'port_id':
port_id})
2014-06
Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
What is in the variable named 'query' that you are trying to merge into the
session? Can you include the full create_port_postcommit method? The line
raising the exception ends with "{'port_id': port_id})" and that doesn't
matching anything included in your sample.
On Wed, Jun 25, 2014 at 6:53 PM, Li Ma wrote:
> Here's a code sample which can raise db lock wait exception:
>
> def create_port_postcommit(self, context):
>
> port_id = ...
> with session.begin(subtransactions=True):
> try:
> binding = (session.query(models.PortBinding).
> filter(models.PortBinding.port_id.startswith(port_id)).
> one())
> # Here I modify some attributes if port binding is existed
> session.merge(query)
> except exc.NoResultFound:
> # Here I insert new port binding record to initialize some
> attributes
> except ...
> LOG.error("error happened")
>
> The exception is as follows:
> 2014-06-25 10:05:17.195 9915 ERROR neutron.plugins.ml2.managers
> [req-961680da-ce69-43c6-974c-57132def411d None] Mechanism driver 'hello'
> failed in create_port_postcommit
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers Traceback
> (most recent call last):
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib/python2.6/site-packages/neutron/plugins/ml2/managers.py", line
> 158, in _call_on_drivers
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> getattr(driver.obj, method_name)(context)
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib/python2.6/site-packages/neutron/plugins/ml2/drivers/mech_hello.py",
> line 95, in create_port_postcommit
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> {'port_id': port_id})
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/session.py",
> line 402, in __exit__
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> self.commit()
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/session.py",
> line 314, in commit
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> self._prepare_impl()
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
> "/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/session.py",
> line 298, in _prepare_impl
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> self.session.flush()
>
> ...
>
> 2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
> OperationalError: (OperationalError) (1205, 'Lock wait timeout exceeded;
> try restarting transaction') 'INSERT INTO ml2_port_bindings (port_id, host,
> vnic_type, profile, vif_type, vif_details, driver, segment) VALUES (%s, %s,
> %s, %s, %s, %s, %s, %s)' (...)
>
> It seems that the transaction in the postcommit cannot be committed.
>
> Thanks a lot,
> Li Ma
>
> - Original Message -
> From: "Li Ma"
> To: "OpenStack Development Mailing List (not for usage questions)" <
> openstack-dev@lists.openstack.org>
> Sent: 星期三, 2014年 6 月 25日 下午 6:21:10
> Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when
> developing new mechanism driver
>
> Hi Kevin,
>
> Thanks for your reply. Actually, it is not that straightforward.
> Even if postcommit is outside the 'with' statement, the transaction is not
> 'truly' committed immediately. Because when I put my db code (reading and
> writing ml2-related tables) in postcommit, db lock wait exception is still
> thrown.
>
> Li Ma
>
> - Original Message -
> From: "Kevin Benton"
> To: "OpenStack Development Mailing List (not for usage questions)" <
> openstack-dev@lists.openstack.org>
> Sent: 星期三, 2014年 6 月 25日 下午 4:59:26
> Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when
> developing new mechanism driver
>
>
>
> The post_commit methods occur outside of the transactions. You should be
> able to perform the necessary database calls there.
>
>
> If you look at the code snippet in the email you provided, you can see
> that the 'try' block surrounding the postcommit method is at the same
> indentation-level as the 'with' statement for the transaction so it will be
> closed at that point.
>
>
> Cheers,
> Ke
Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
Here's a code sample which can raise db lock wait exception:
def create_port_postcommit(self, context):
port_id = ...
with session.begin(subtransactions=True):
try:
binding = (session.query(models.PortBinding).
filter(models.PortBinding.port_id.startswith(port_id)).
one())
# Here I modify some attributes if port binding is existed
session.merge(query)
except exc.NoResultFound:
# Here I insert new port binding record to initialize some attributes
except ...
LOG.error("error happened")
The exception is as follows:
2014-06-25 10:05:17.195 9915 ERROR neutron.plugins.ml2.managers
[req-961680da-ce69-43c6-974c-57132def411d None] Mechanism driver 'hello' failed
in create_port_postcommit
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers Traceback (most
recent call last):
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib/python2.6/site-packages/neutron/plugins/ml2/managers.py", line 158,
in _call_on_drivers
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
getattr(driver.obj, method_name)(context)
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib/python2.6/site-packages/neutron/plugins/ml2/drivers/mech_hello.py",
line 95, in create_port_postcommit
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers {'port_id':
port_id})
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/session.py",
line 402, in __exit__
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
self.commit()
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/session.py",
line 314, in commit
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
self._prepare_impl()
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers File
"/usr/lib64/python2.6/site-packages/SQLAlchemy-0.7.8-py2.6-linux-x86_64.egg/sqlalchemy/orm/session.py",
line 298, in _prepare_impl
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
self.session.flush()
...
2014-06-25 10:05:17.195 9915 TRACE neutron.plugins.ml2.managers
OperationalError: (OperationalError) (1205, 'Lock wait timeout exceeded; try
restarting transaction') 'INSERT INTO ml2_port_bindings (port_id, host,
vnic_type, profile, vif_type, vif_details, driver, segment) VALUES (%s, %s, %s,
%s, %s, %s, %s, %s)' (...)
It seems that the transaction in the postcommit cannot be committed.
Thanks a lot,
Li Ma
- Original Message -
From: "Li Ma"
To: "OpenStack Development Mailing List (not for usage questions)"
Sent: 星期三, 2014年 6 月 25日 下午 6:21:10
Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing
new mechanism driver
Hi Kevin,
Thanks for your reply. Actually, it is not that straightforward.
Even if postcommit is outside the 'with' statement, the transaction is not
'truly' committed immediately. Because when I put my db code (reading and
writing ml2-related tables) in postcommit, db lock wait exception is still
thrown.
Li Ma
- Original Message -----
From: "Kevin Benton"
To: "OpenStack Development Mailing List (not for usage questions)"
Sent: 星期三, 2014年 6 月 25日 下午 4:59:26
Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing
new mechanism driver
The post_commit methods occur outside of the transactions. You should be able
to perform the necessary database calls there.
If you look at the code snippet in the email you provided, you can see that the
'try' block surrounding the postcommit method is at the same indentation-level
as the 'with' statement for the transaction so it will be closed at that point.
Cheers,
Kevin Benton
--
Kevin Benton
On Tue, Jun 24, 2014 at 8:33 PM, Li Ma < skywalker.n...@gmail.com > wrote:
Hi all,
I'm developing a new mechanism driver. I'd like to access ml2-related tables in
create_port_precommit and create_port_postcommit. However I find it hard to do
that because the two functions are both inside an existed database transaction
defined in create_port function of ml2/plugin.py.
The related code is as follows:
def create_port(self, context, port):
...
session = context.session
with session.begin(subtransactions=True):
...
self.mechanism_manager.create_port_precommit(mech_context)
try:
self.mechanism_manager.create_port_postcommit(mech_context)
...
...
return result
As a result, I need to carefully deal with the database nested transaction
issue to prevent from db lock when I develop my own mechanism
Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
I'm not sure what you mean about it being 'truly committed' even though the
transaction has ended. When would it be committed? There are not more calls
to sqlalchemy after that. The only way it wouldn't be committed is if
another transaction was started before calling create_port.
Regardless, a db lock wait exception does not indicate anything about the
state of a particular transaction. Transactions do not lock tables on their
own. A lock has to be explicitly set with a "with_lockmode('update')" on a
query.
I think you will probably need to share some sample code with the mailing
list demonstrating what you are trying to do.
--
Kevin Benton
On Wed, Jun 25, 2014 at 3:21 AM, Li Ma wrote:
> Hi Kevin,
>
> Thanks for your reply. Actually, it is not that straightforward.
> Even if postcommit is outside the 'with' statement, the transaction is not
> 'truly' committed immediately. Because when I put my db code (reading and
> writing ml2-related tables) in postcommit, db lock wait exception is still
> thrown.
>
> Li Ma
>
> - Original Message -
> From: "Kevin Benton"
> To: "OpenStack Development Mailing List (not for usage questions)" <
> openstack-dev@lists.openstack.org>
> Sent: 星期三, 2014年 6 月 25日 下午 4:59:26
> Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when
> developing new mechanism driver
>
>
>
> The post_commit methods occur outside of the transactions. You should be
> able to perform the necessary database calls there.
>
>
> If you look at the code snippet in the email you provided, you can see
> that the 'try' block surrounding the postcommit method is at the same
> indentation-level as the 'with' statement for the transaction so it will be
> closed at that point.
>
>
> Cheers,
> Kevin Benton
>
>
> --
> Kevin Benton
>
>
>
> On Tue, Jun 24, 2014 at 8:33 PM, Li Ma < skywalker.n...@gmail.com > wrote:
>
>
> Hi all,
>
> I'm developing a new mechanism driver. I'd like to access ml2-related
> tables in create_port_precommit and create_port_postcommit. However I find
> it hard to do that because the two functions are both inside an existed
> database transaction defined in create_port function of ml2/plugin.py.
>
> The related code is as follows:
>
> def create_port(self, context, port):
> ...
> session = context.session
> with session.begin(subtransactions=True):
> ...
> self.mechanism_manager.create_port_precommit(mech_context)
> try:
> self.mechanism_manager.create_port_postcommit(mech_context)
> ...
> ...
> return result
>
> As a result, I need to carefully deal with the database nested transaction
> issue to prevent from db lock when I develop my own mechanism driver. Right
> now, I'm trying to get the idea behind the scene. Is it possible to
> refactor it in order to make precommit and postcommit out of the db
> transaction? I think it is perfect for those who develop mechanism driver
> and do not know well about the functioning context of the whole ML2 plugin.
>
> Thanks,
> Li Ma
>
> ___
> OpenStack-dev mailing list
> OpenStack-dev@lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
>
>
>
> --
>
> Kevin Benton
> ___
> OpenStack-dev mailing list
> OpenStack-dev@lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
> ___
> OpenStack-dev mailing list
> OpenStack-dev@lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
--
Kevin Benton
___
OpenStack-dev mailing list
OpenStack-dev@lists.openstack.org
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Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
Hi Kevin, Thanks for your reply. Actually, it is not that straightforward. Even if postcommit is outside the 'with' statement, the transaction is not 'truly' committed immediately. Because when I put my db code (reading and writing ml2-related tables) in postcommit, db lock wait exception is still thrown. Li Ma - Original Message - From: "Kevin Benton" To: "OpenStack Development Mailing List (not for usage questions)" Sent: 星期三, 2014年 6 月 25日 下午 4:59:26 Subject: Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver The post_commit methods occur outside of the transactions. You should be able to perform the necessary database calls there. If you look at the code snippet in the email you provided, you can see that the 'try' block surrounding the postcommit method is at the same indentation-level as the 'with' statement for the transaction so it will be closed at that point. Cheers, Kevin Benton -- Kevin Benton On Tue, Jun 24, 2014 at 8:33 PM, Li Ma < skywalker.n...@gmail.com > wrote: Hi all, I'm developing a new mechanism driver. I'd like to access ml2-related tables in create_port_precommit and create_port_postcommit. However I find it hard to do that because the two functions are both inside an existed database transaction defined in create_port function of ml2/plugin.py. The related code is as follows: def create_port(self, context, port): ... session = context.session with session.begin(subtransactions=True): ... self.mechanism_manager.create_port_precommit(mech_context) try: self.mechanism_manager.create_port_postcommit(mech_context) ... ... return result As a result, I need to carefully deal with the database nested transaction issue to prevent from db lock when I develop my own mechanism driver. Right now, I'm trying to get the idea behind the scene. Is it possible to refactor it in order to make precommit and postcommit out of the db transaction? I think it is perfect for those who develop mechanism driver and do not know well about the functioning context of the whole ML2 plugin. Thanks, Li Ma ___ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev -- Kevin Benton ___ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev ___ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
Re: [openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
The post_commit methods occur outside of the transactions. You should be able to perform the necessary database calls there. If you look at the code snippet in the email you provided, you can see that the 'try' block surrounding the postcommit method is at the same indentation-level as the 'with' statement for the transaction so it will be closed at that point. Cheers, Kevin Benton -- Kevin Benton On Tue, Jun 24, 2014 at 8:33 PM, Li Ma wrote: > Hi all, > > I'm developing a new mechanism driver. I'd like to access ml2-related > tables in create_port_precommit and create_port_postcommit. However I find > it hard to do that because the two functions are both inside an existed > database transaction defined in create_port function of ml2/plugin.py. > > The related code is as follows: > > def create_port(self, context, port): > ... > session = context.session > with session.begin(subtransactions=True): > ... > self.mechanism_manager.create_port_precommit(mech_context) > try: > self.mechanism_manager.create_port_postcommit(mech_context) > ... > ... > return result > > As a result, I need to carefully deal with the database nested transaction > issue to prevent from db lock when I develop my own mechanism driver. Right > now, I'm trying to get the idea behind the scene. Is it possible to > refactor it in order to make precommit and postcommit out of the db > transaction? I think it is perfect for those who develop mechanism driver > and do not know well about the functioning context of the whole ML2 plugin. > > Thanks, > Li Ma > > ___ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > -- Kevin Benton ___ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
[openstack-dev] [Neutron ML2] Potential DB lock when developing new mechanism driver
Hi all, I'm developing a new mechanism driver. I'd like to access ml2-related tables in create_port_precommit and create_port_postcommit. However I find it hard to do that because the two functions are both inside an existed database transaction defined in create_port function of ml2/plugin.py. The related code is as follows: def create_port(self, context, port): ... session = context.session with session.begin(subtransactions=True): ... self.mechanism_manager.create_port_precommit(mech_context) try: self.mechanism_manager.create_port_postcommit(mech_context) ... ... return result As a result, I need to carefully deal with the database nested transaction issue to prevent from db lock when I develop my own mechanism driver. Right now, I'm trying to get the idea behind the scene. Is it possible to refactor it in order to make precommit and postcommit out of the db transaction? I think it is perfect for those who develop mechanism driver and do not know well about the functioning context of the whole ML2 plugin. Thanks, Li Ma ___ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
