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Re: subversion client scalability (was Re: subversion 1.3.1 + apr 0.9.7 = memory leak?)

From: David Young <dyoung_at_pobox.com>
Date: 2006-06-14 00:18:01 CEST

On Thu, May 04, 2006 at 02:34:11PM -0500, David Young wrote:
> On Wed, May 03, 2006 at 10:05:29PM -0700, Garrett Rooney wrote:
> > On 5/3/06, David Young <dyoung@pobox.com> wrote:
> > >I have installed Subversion 1.3.1 and APR 0.9.7 from pkgsrc on a NetBSD
> > >3.99.7 box. I created a fresh fsfs database and svn import'd the
> > >entire NetBSD source tree.
> > >
> > >When I run commands such as 'svn co' and 'svn status -u' on the
> > >repository, they take several minutes to run (i.e., too long), and svn's
> > >memory usage climbs to 150MB, which seems unusually high. This is not
> > >acceptable performance in my application, and I am wondering if there is
> > >some easy way to speed up operations on large repositories such as mine.
> > >
> > >I have scanned the users@subversion mailing list archives for others'
> > >reports about high memory usage and slow commands, and I do not find
> > >any reports concerning 1.3.x.
> > >
> > >I am beginning to suspect that a memory leak in APR 0.9.7 is behind the
> > >high memory usage. Can anyone confirm? Do most people use APR 1.2 with
> > >Subversion 1.3.1?
> >
> > Operations on large working copies (including checkout and status)
> > will use amounts of memory proportional to its size, due to the
> > caching of information about the entries in each directory. It's
> > either that or you get unacceptable speed hits from parsing the
> > entries file multiple times. The version of APR you use will probably
> > have no noticable effect on memory usage, and Subversion 1.3.1 is not
> > especially worse in this regard than previous versions (although it
> > might be slightly worse due to a slightly larger entries object, I
> > can't recall).
> It seems that the cache grows without bound, without regard for the
> potential of thrashing. It ceases to improve performance after a while.
> What is the rule for kicking entries out of the cache? Can I reduce
> the cache size?
> I am surprised that the cost of re-parsing is so great that it pays to
> keep a parsed entries object in the cache, especially when the OS holds
> the unparsed entries file in disk cache. I am probably just missing
> something.

This email, bumping issue 2167 from milestone 1.4 to 1.5, crossed my desk
a while ago. 2167 is an aging report on facets of the client scalability
problem discussed in this thread. I was startled by the bump. Is there
a consensus in the Subversion leadership that the client's scalability
should be a lower priority than before?



Date: 21 May 2006 18:29:48 -0000
From: lundblad@tigris.org
To: shepard@tigris.org
Subject: [UTF-8] [Issue 2167] core dump while checking o[UTF-8] ut a copy
    of large repository


User lundblad changed the following:

                What |Old value |New value
        Target milestone|1.4 |1.5

------- Additional comments from lundblad@tigris.org Sun May 21 11:29:48 -0700
2006 -------
We're using memory proportional to the working copy size, that's because we
cache the entries. I'm pushing this issue to 1.5; I think our out-of-memory
handler should say at least say something before aborting().

David Young             OJC Technologies
dyoung@ojctech.com      Urbana, IL * (217) 278-3933
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Received on Wed Jun 14 00:19:28 2006

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