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svn+ssh children for svn:externals pile up

From: toby cabot <toby_at_caboteria.org>
Date: Fri, 16 Oct 2009 11:19:52 -0400

Hi Subversion Folks,

I use subversion at work and it works well. Thanks! We've recently
started using svn:externals in a big way and are starting to see "svn
update" fail because svn spawns an ssh child for each svn:external and
they "stack up" until the count exhausts the limit of processes that
macos lets one user fork (266 by default, I think). I can work around
the problem by increasing those limits but that's not a long-term
solution.

I trolled the svn bug tracker and bug 2580[1] looked relevant. It
indicated that there's a bug[2] in openssh's server that combined with
svn's process handling caused ssh child processes to not exit cleanly.
Sure enough, our linux server has the ssh bug, so I built svn 1.6.5
from source and tried it on an Ubuntu 2009.10 server that has a fixed
ssh server (as verified by the test mentioned in 2580's bug report).

That didn't work either. It looks as if svn, even with the fix in
2580, spawns one ssh client for each svn:external and those clients
don't exit - they just stack up until the parent "svn up" is finished:

/home/tcabot/Downloads/subversion-1.6.5/subversion/svn/.libs/lt-svn up
 \_ ssh -q -o ControlMaster=no data1.dev svnserve -t
 \_ ssh -q -o ControlMaster=no data1.dev svnserve -t
 \_ ssh -q -o ControlMaster=no data1.dev svnserve -t
 \_ ssh -q -o ControlMaster=no data1.dev svnserve -t
 \_ ssh -q -o ControlMaster=no data1.dev svnserve -t
 etc...

If it helps, this behavior is better than svn versions up through
1.6.4 that (at least on the mac) would spawn *two* children per
svn:external:

12579 s000 Z+ 0:00.00 (ssh)
12580 s000 S+ 0:00.07 ssh data1.dev svnserve -t

Any ideas? If you can think of any experiments for me to run, I'd be
happy to do so.

Thanks,
Toby Cabot

[1] http://subversion.tigris.org/issues/show_bug.cgi?id=2580
[2] https://bugzilla.mindrot.org/show_bug.cgi?id=85

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Received on 2009-10-16 17:22:04 CEST

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