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Re: svn commit: r1588651 - in /subversion/trunk/subversion/libsvn_fs_fs: caching.c fs.c fs_fs.h

From: Ivan Zhakov <ivan_at_visualsvn.com>
Date: Sat, 19 Apr 2014 19:35:18 +0400

On 19 April 2014 19:25, Branko Čibej <brane_at_wandisco.com> wrote:
> On 19.04.2014 17:12, Ivan Zhakov wrote:
> On 19 April 2014 16:44, <stefan2_at_apache.org> wrote:
> Author: stefan2
> Date: Sat Apr 19 12:44:07 2014
> New Revision: 1588651
> URL: http://svn.apache.org/r1588651
> Log:
> Reduce the size of an FSFS instance by using temporary pools
> for temp. data during fs_open().
> * subversion/libsvn_fs_fs/fs_fs.h
> (svn_fs_fs__initialize_caches): Document that the POOL shall be
> used for temporaries only.
> * subversion/libsvn_fs_fs/caching.c
> (svn_fs_fs__initialize_caches): Fix the only place where we used
> POOL instead of FS->POOL for
> something with svn_fs_t lifetime.
> * subversion/libsvn_fs_fs/fs.c
> (fs_serialized_init): Document POOL usage that we will now rely on.
> (fs_open): Use a SUBPOOL for anything temporary during FS init.
> Just creating subpool for temporary allocation violates pool design
> imho. Proper fix would be add scratch pool parameter to
> svn_fs_open()/svn_fs_create().
Hi Branko,

> Doesn't "violate" it, as such ... there's a balance to be maintained here.
I agree about balance, but general idea of pool design that caller
controls memory usage of callee.

> Adding a scratch-pool parameter means revising the API and propagating the
> revision up the call chain to all the places where a meaningful scratch pool
> is already available. Sure it's better to do do that in the long run; but
> does the change warrant the related code churn now? Consider that there's a
> vtable involved here, too.
I still prefer adding scratch_pool: users interested of improved
memory usage (like mod_dav_svn) can use new API. Btw memory usage may
increase in some cases with subpools: every pool consumes 8k of
memory, subpools are not cleared on error in general. So we got 8k
memory wasted on error cases.

Ivan Zhakov
CTO | VisualSVN | http://www.visualsvn.com
Received on 2014-04-19 17:36:11 CEST

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