Re: Any know problems with worker MPM and mod_dav_svn?

Justin Erenkrantz <jerenkrantz@apache.org> writes:

> > I've been experimenting and I'm seeing occasional failures when
> > using Apache's worker MPM that I don't see when using the prefork
> > MPM. Are there any known issues combining mod_dav_svn and worker?
>
> Hmm. Shouldn't be.

Then I better not ignore the probem!

> > The errors occur at commit, one is a failure to read the repository
> > format file and the other is a failure to open the db lock file.
> > They are transient, an earlier commit has succeeded and a later
> > commit also works.
>
> Can you consistently reproduce this transient error? (Does it happen
> once out of every five times you try?)

I can consistently reproduce it, but it is irregular. I've
deliberately configured Apache to use a small number of threads

StartServers 1
MaxClients 6
MinSpareThreads 1
MaxSpareThreads 2
ThreadsPerChild 6
MaxRequestsPerChild 0

and I'm running 3 instances of the tools/dev/stress.pl script, so
that's 3 separate working copies committing to the same repository. I
can commit hundreds of revisions using prefork, but with worker the
errors usually occur after a few tens of revisions, although on one
occasion I saw over 100 revisions before it failed.

The error will stop one of the script instances (which usually has
committed several times) but the other instances carry on and continue
to commit.

> The only thing I can think of is something within SVN (or BDB) isn't
> playing nice with threads.

I using Apache/Subversion HEAD and BDB 4.1, all built from source.

> BTW, what OS are you using (I think you are a Linux user, but not 100%
> sure)? Some OSes do have shaky thread support. -- justin

Linux, more or less plain Debian/stable. It's a 2-way SMP machine
running kernel 2.4.19.

-- 
Philip Martin
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