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
> > > > > > > > browser.
>
> > > > > > > > We've picked up the recent 3/13/09 nightly which has helped
> > > > > enormously
> > > > > > > > (A BIG THANKS!) but that said, we're still finding pages that
> > > take 3+
> > > > > > > > minutes to load.
>
> > > > > > > > For example.... we have one review in particular that has File
> > > > > Changes
> > > > > > > > spread over 6 ReviewBoard pages. Page 3 takes on average 3+
> > > minutes
> > > > > to
> > > > > > > > load. It also readily crashes my browser - pegging my CPU and I
> > > have
> > > > > > > > to kill the session. (URL=
> > >https://reviewboard/r/2808/diff/?page=3).
> > > > > > > > This is in FireFox 3.0.7. Under IE the page doesn't load without
> > > > > > > > running into script errors. Unfortunately, these large
> > > ReviewBoard
> > > > > > > > diffs are a typical use case at our company (typically when 
> > > > > > > > large
> > > > > > > > merges are done) and breaking things across more than 10 reviews
> > > jsut
> > > > > > > > isn't plausible. I should mention that not only are the diff
> > > > > fragments
> > > > > > > > themselves large for these use cases but the number of reviewers
> > > and
> > > > > > > > comments gets to be very large too. We're maxing out what
> > > ReviewBoard
> > > > > > > > can handle on all fronts.
>
> > > > > > > > Can further investigation be done into these performance issues
> > > for
> > > > > > > > us? I will supply further information as I collect it.
>
> > > > > > > > Thanks,
> > > > > > > > Mary- Hide quoted text -
>
> > > > > > > - Show quoted text -- Hide quoted text -
>
> > > > > > - Show quoted text -- Hide quoted text -
>
> > > > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
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