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Re: Why does SVN + apache try to close non existing file descriptors?

From: Erik Huelsmann <ehuels_at_gmail.com>
Date: Wed, 12 Mar 2008 17:44:01 +0100

On 3/12/08, Jon Bendtsen <jbendtsen_at_laerdal.dk> wrote:
> Hi
> I have a problem with SVN and/or apache which does not apply to
> svnserve.
> I use svn log to test this, but my users complain that any SVN command
> is slow.
> Using svnserve directly it takes less than a second to get an output
> of svn log.
> Using SVN through apache it takes about 28 minutes to get a log.
> So i used strace on apache and it turns out it tries to close
> 1024*1024 file descriptors
> more than once. Every time takes almost a minute. It starts 41 times,
> but for some reason
> it does not count to 1024*1024 every time. But it does count to
> 1024*1024 22 times,
> and some times only to some hundred thousand times. The error message
> is like this
> 13:47:17 close(227260) = -1 EBADF (Bad file descriptor)
> Most of the times the processes only have a few files open, so
> anything after 2 or 3
> gets an error message. This means i get a strace file with 1024 * 1024
> error lines.
> Q) why brute force close all files?

I think this is an apache or APR question: I can't think of any reason
why Subversion would be closing file handles. I *can* see reasons why
Apache would do that when starting a client to handle a request. Which
MPM did you configure for your Apache? mpm_worker? mpm_prefork?

> a) ask the kernel to close all my open files
> b) ask the kernel which files do I have open and then close only those
> c) remember what files i have open and then close only those

I think this would have been implemented by the Apache folks if it
could be done reliably: they're very keen on performance. Maybe you
could try the same question with them?



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Received on 2008-03-12 17:44:49 CET

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