That's great to hear, thanks! I will stay tuned...

On Fri, Mar 27, 2009 at 2:27 PM, Christian Hammond <chip...@chipx86.com>wrote:

> Okay, I have a couple ideas now where the problem lies.
>
> I want to give you a heads up that we'll be releasing beta 1 soon, and it
> won't include a fix for this. This is going to be a much larger problem to
> tackle and I don't want to hold up this release (since it has many very
> important fixes in it). I hope to get to this one for beta 2.
>
> Christian
>
> --
> Christian Hammond - chip...@chipx86.com
> Review Board - http://www.review-board.org
> VMware, Inc. - http://www.vmware.com
>
>
>   On Fri, Mar 27, 2009 at 10:27 AM, ciaomary <ciaom...@gmail.com> wrote:
>
>>
>> We typically only see perf problems on reviews with large diffs and
>> large number of reviews. One that has given us a lot of trouble has a
>> downloadable diff of 1.6MB, 138 different files (with an average file
>> size of ~30K), and hundreds+ review comments. (Bringing up diffs for
>> deleted files give the biggest load and slow down.)
>>
>> Under Admin Settings I've changed the "Paginate by" value from 20 down
>> to just 3 which has helped a lot. It is set to the default 5 "Lines of
>> Context". Also increasing the RAM on our server from 4G to 16G has
>> helped - RB takes a lot of server memory under this kind of load!
>> After all this we're still seeing these big reviews taking 45-60
>> seconds to load, pegging local cpu during that time.
>>
>> I suspect you could reproduce this by setting the "Paginate by" value
>> to something very high. (Try 55 for your 55 page diff.) I believe the
>> problem is only on reviews with lots of comments as well. Our use case
>> has been that if there is a really large diff, there are always a lot
>> of review comments as well.
>>
>> Thanks!
>>
>> On Mar 27, 1:38 am, Christian Hammond <chip...@chipx86.com> wrote:
>> > So I just looked at a diff on our server that spans 55 pages, and as far
>> as
>> > loading diffs goes, it's not at all slow. How many pages did you say
>> yours
>> > were on average?
>> >
>> > When looking at diffs, do you have it set to expand the entire file, or
>> show
>> > the collapsed version?
>> >
>> > Are you seeing slowdown on large diffs that don't have any reviews, or
>> is it
>> > just when there's a lot of reviews for that revision of the diff?
>> >
>> > Christian
>> >
>> > --
>> > Christian Hammond - chip...@chipx86.com
>> > Review Board -http://www.review-board.org
>> > VMware, Inc. -http://www.vmware.com
>> >
>> > On Mon, Mar 23, 2009 at 5:02 PM, Christian Hammond <chip...@chipx86.com
>> >wrote:
>> >
>> >
>> >
>> > > I'm still looking into it. So far I have not seen the slowdown you
>> have
>> > > described, but will continue to try to figure out what's going on. I
>> know
>> > > this is inconvenient. We just haven't seen usage like this yet.
>> >
>> > > Christian
>> >
>> > > --
>> > > Christian Hammond - chip...@chipx86.com
>> > > Review Board -http://www.review-board.org
>> > > VMware, Inc. -http://www.vmware.com
>> >
>>  > > On Mon, Mar 23, 2009 at 1:19 PM, ciaomary <ciaom...@gmail.com>
>> wrote:
>> >
>> > >> Any follow up on this? Any configuration guidance?
>> >
>> > >> We've moved to a 16 G + 4 cpu system and still have unacceptable
>> > >> response times (~30 seconds) for really large diffs with hundreds of
>> > >> review comments.
>> >
>> > >> If you can't reproduce this, I recommend you set the number of diff
>> > >> files per page from 20 to something really high (like 100) and then
>> > >> post a review with the same number of files deleted. For us, this
>> puts
>> > >> a huge load on the local browser and the server VM during load.
>> >
>> > >> On Mar 19, 12:41 pm, ciaomary <ciaom...@gmail.com> wrote:
>> > >> > Thanks again. I'm really not that familiar with Apache 2 w/ regards
>> to
>> > >> > performance issues. At this time, I just have a more or less
>> out-of-
>> > >> > the-box Apache2 setup on CentOS 5. Any recommendations here would
>> be
>> > >> > hugely appreciated. Further answers inline below...
>> >
>> > >> > On Mar 19, 12:09 pm, Christian Hammond <chip...@chipx86.com>
>> wrote:
>> >
>> > >> > > We should figure out first why your backend server is being hit
>> so
>> > >> hard. We
>> > >> > > have over a thousand people at VMware submitting good sized diffs
>> and
>> > >> aren't
>> > >> > > hitting any of these issues. So a few more questions. Apologies
>> if
>> > >> you've
>> > >> > > answered these before in other threads.
>> >
>> > >> > > 1) What MPM is your Apache using?
>> >
>> > >> > I'm using the default for httpd 2.2.3 CentOS. I believe this is
>> > >> > 'prefork'.
>> >
>> > >> > > 2) And is this fastcgi or mod_python?
>> >
>> > >> > mod_python (mod_python-3.2.8-3.1)
>> >
>> > >> > > 3) Are you absolutely sure Review Board is using your memcached
>> > >> server? Go
>> > >> > > in the admin dashboard and click Server Cache, then copy and
>> paste the
>> > >> info
>> > >> > > and paste it here.
>> >
>> > >> > Server Cache
>> > >> > Cache backend: django.core.cache.backends.memcached
>> > >> > Statistics
>> > >> > 127.0.0.1:11211 Memory usage:   45.7 MB
>> > >> > Keys in cache:  1767 of 1777
>> > >> > Cache hits:     3996 of 7464: 53%
>> > >> > Cache misses:   3468 of 7464: 46%
>> > >> > Cache evictions:        0
>> > >> > Cache traffic:  46.1 MB in, 103.8 MB out
>> > >> > Uptime:         53009
>> >
>> > >> > > We might be able to do something smarter with deleted diffs, but
>> that
>> > >> would
>> > >> > > require a good bit of work, and we'd have to think carefully
>> about it.
>> >
>> > >> > > We talked about splitting up the reviews page, but decided it
>> wouldn't
>> > >> make
>> > >> > > much sense due to how it's ordered. We came up with a method for
>> > >> collapsing,
>> > >> > > but  I'm probably holding off until after 1.0 to finish this,
>> because
>> > >> it
>> > >> > > needs a lot more thought and testing.
>> >
>> > >> > > Christian
>> >
>> > >> > > --
>> > >> > > Christian Hammond - chip...@chipx86.com
>> > >> > > Review Board -http://www.review-board.org
>> > >> > > VMware, Inc. -http://www.vmware.com
>> >
>> > >> > > On Thu, Mar 19, 2009 at 11:39 AM, ciaomary <ciaom...@gmail.com>
>> > >> wrote:
>> >
>> > >> > > > Thanks for your response. Please see comments inline below...
>> >
>> > >> > > > On Mar 18, 11:35 am, Christian Hammond <chip...@chipx86.com>
>> wrote:
>> > >> > > > > Not immediately, no.
>> >
>> > >> > > > > I can't even determine right now whether we can do anything
>> about
>> > >> this.
>> > >> > > > > You're seeing crazy CPU loads that we're definitely not
>> seeing,
>> > >> and most
>> > >> > > > of
>> > >> > > > > this has to do with the browser itself. We're loading the
>> files
>> > >> > > > > asynchronously, but it appears that for whatever reason your
>> > >> browser is
>> > >> > > > > blocking until it's all loaded (if I'm understanding right).
>> >
>> > >> > > > Just for clarity, the page can sometimes load partially, but
>> since
>> > >> the
>> > >> > > > CPU is at 99% it's of little value. I don't get the CPU back
>> until
>> > >> the
>> > >> > > > page is fully loaded.
>> >
>> > >> > > > We now understand that our backend server is also getting maxed
>> out
>> > >> to
>> > >> > > > the point of failure. One request of this page demands 800 M of
>> > >> > > > virtual memory from Apache! Once the request is fully loaded,
>> 400 M
>> > >> of
>> > >> > > > that memory is freed again - but since we have 200 reviewboard
>> users
>> > >> > > > this isn't very scalable.
>> >
>> > >> > > > > I'm wondering
>> > >> > > > > if there's something with the configuration in your browsers
>> where
>> > >> you
>> > >> > > > work
>> > >> > > > > that is causing some of this.
>> >
>> > >> > > > I really don't think this is a browser configuration issue
>> because
>> > >> > > > users across many different OS and browsers are seeing this. I
>> see
>> > >> it
>> > >> > > > on default FireFox 3.0.7 and IE 7.0. Users have reported that
>> Safari
>> > >> > > > works the best, but I have not confirmed. FireFox 2 and IE 6
>> users
>> > >> > > > have reported the same problem.
>> >
>> > >> > > > > You say this is happening on several different browsers? In
>> the
>> > >> case of
>> > >> > > > > Firefox, what extensions are loaded?
>> >
>> > >> > > > Just the default FireFox 3.0.7 install.
>> >
>> > >> > > > > We definitely would like to fix this. But we just don't know
>> > >> enough about
>> > >> > > > > what the problem is right now to determine if it's in our
>> control.
>> >
>> > >> > > > Apache must load up a huge amount of data in VM for these large
>> > >> diffs
>> > >> > > > (I believe this is especially true when diffs contain deleted
>> > >> files).
>> > >> > > > This isn't scalable across many users. Can the amount of data/
>> > >> > > > filediffs/etc needed to load the page be scaled back further?
>> > >> Changing
>> > >> > > > the 'Paginate by' value from 20 to 3 has helped, but not enough
>> and
>> > >> it
>> > >> > > > hasn't helped the review page obviously.
>> >
>> > >> > > > Instead of showing all lines for deleted files can this be
>> loaded
>> > >> > > > later only on request?
>> > >> > > > Can the 'View Reviews' page be broken up or paginated as well?
>> > >> > > > I think these two suggestions would help us.
>> >
>> > >> > > > > Christian
>> >
>> > >> > > > > --
>> > >> > > > > Christian Hammond - chip...@chipx86.com
>> > >> > > > > Review Board -http://www.review-board.org
>> > >> > > > > VMware, Inc. -http://www.vmware.com
>> >
>> > >> > > > > On Wed, Mar 18, 2009 at 9:54 AM, ciaomary <
>> ciaom...@gmail.com>
>> > >> wrote:
>> >
>> > >> > > > > > Can anything be done to fix the pegged CPU issue I've
>> reported
>> > >> in my
>> > >> > > > > > prior email?
>> >
>> > >> > > > > > On Mar 17, 9:38 am, ciaomary <ciaom...@gmail.com> wrote:
>> > >> > > > > > > The downloadable diff for the review is 1.6MB.
>> >
>> > >> > > > > > > The review has 138 different files (7 pages).
>> >
>> > >> > > > > > > Page 1 loads in ~1 minute in FireFox. The twenty files
>> are on
>> > >> average
>> > >> > > > > > > 38 K. (max=118K, min=2K). Here all files have edit
>> changes (no
>> > >> > > > deleted
>> > >> > > > > > > files.)
>> >
>> > >> > > > > > > Page 3 loads in ~3 minutes in FireFox. The twenty files
>> are on
>> > >> > > > average
>> > >> > > > > > > 25K . No major deviations from the average. Here 12 of
>> the
>> > >> files have
>> > >> > > > > > > been deleted rather than just edited.
>> >
>> > >> > > > > > > There are hundreds of review comments on this review
>> across
>> > >> many
>> > >> > > > users
>> > >> > > > > > > and files.
>> >
>> > >> > > > > > > During page load, the CPU is pegged and the browser is
>> > >> unresponsive
>> > >> > > > > > > for a good 2-3 minutes. This is the cause every time,
>> very
>> > >> > > > > > > reproducable. If you are patient the page finally loads
>> and
>> > >> the
>> > >> > > > system
>> > >> > > > > > > CPU returns to normal.
>> >
>> > >> > > > > > > FireBug shows an HTTPS GET request for each of the twenty
>> > >> files
>> > >> > > > during
>> > >> > > > > > > the slow down/cpu pegging. Each HTTPS GETS are taking
>> longer
>> > >> on page
>> > >> > > > > > > 3, with some taking up to 2.5 seconds (others < 50ms).
>> Since
>> > >> the is
>> > >> > > > > > > cpu is pegged the browser processing seems to be the
>> cause of
>> > >> the
>> > >> > > > > > > delay however.
>> >
>> > >> > > > > > > On Mar 16, 6:31 pm, Christian Hammond <
>> chip...@chipx86.com>
>> > >> wrote:
>> >
>> > >> > > > > > > > So it's really going to depend on the sizes of the
>> > >> individual files
>> > >> > > > > > > > themselves. If a file is by itself large enough to
>> cause a
>> > >> couple
>> > >> > > > meg
>> > >> > > > > > diff
>> > >> > > > > > > > to be generated, there's nothing we can do really do,
>> since
>> > >> that
>> > >> > > > boils
>> > >> > > > > > down
>> > >> > > > > > > > to too large a file to show in the browser.
>> >
>> > >> > > > > > > > In your page 3 example, how big are the files and the
>> diffs
>> > >> in
>> > >> > > > > > particular?
>> >
>> > >> > > > > > > > The page itself loads quick enough, right? It's just
>> the
>> > >> diff
>> > >> > > > > > fragments?
>> > >> > > > > > > > Which ones are you finding takes a long time and how
>> big are
>> > >> those
>> > >> > > > > > changes?
>> >
>> > >> > > > > > > > Christian
>> >
>> > >> > > > > > > > --
>> > >> > > > > > > > Christian Hammond - chip...@chipx86.com
>> > >> > > > > > > > Review Board -http://www.review-board.org
>> > >> > > > > > > > VMware, Inc. -http://www.vmware.com
>> >
>> > >> > > > > > > > On Mon, Mar 16, 2009 at 5:32 PM, mary <
>> ciaom...@gmail.com>
>> > >> wrote:
>> >
>> > >> > > > > > > > > On really large diffs, performance is very slow and
>> can
>> > >> crash the
>> >
>> > ...
>> >
>> > read more ยป- Hide quoted text -
>>  >
>> > - Show quoted text -
>>
>>
>
> >
>

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