repository sync with large Subversion repository has memory leaks

[Jun Omae]

I got that repository sync command with large Subversion repository eats huge memory in production environment.

• Subversion 1.9.7
• 14 GB
• 48665 revisions
• Memory usage: 9 GB+

Investigating tracopt.versioncontrol.svn, I noticed repos.RevisionChangeCollector has a memory leak. According to comments of the collector, it is deprecated and ChangeCollector should be used. Using repos.ChangeCollector would reduce the memory usage, but other memory leaks still exist….

tracopt/versioncontrol/svn/svn_fs.py

@@ -1017 +1017 @@
         pool = Pool(self.pool)
         tmp = Pool(pool)
         root = fs.revision_root(self.fs_ptr, self.rev, pool())
-        editor = repos.RevisionChangeCollector(self.fs_ptr, self.rev, pool())
+        try:
+            editor = repos.ChangeCollector(self.fs_ptr, root, pool())
+        except AttributeError:
+            editor = repos.RevisionChangeCollector(self.fs_ptr, self.rev,
+                                                   pool())
         e_ptr, e_baton = delta.make_editor(editor, pool())
         repos.svn_repos_replay(root, e_ptr, e_baton, pool())
 

RSS of repository sync on Trac 1.0-stable with mirror of svn.edgewall.org/repos/trac:

Rev	RSS (before patch)	RSS (after patch)	after/before
1	62,726,144	62,713,856	99.98%
1000	101,126,144	84,533,248	83.59%
2000	128,217,088	95,047,680	74.13%
3000	160,608,256	110,559,232	68.84%
4000	191,225,856	124,428,288	65.07%
5000	218,836,992	134,868,992	61.63%
6000	247,250,944	146,202,624	59.13%
7000	277,291,008	159,305,728	57.45%
8000	305,885,184	170,926,080	55.88%
9000	332,189,696	180,367,360	54.30%
10000	356,847,616	188,334,080	52.78%
11000	382,246,912	196,726,784	51.47%
12000	409,014,272	206,376,960	50.46%
13000	434,835,456	215,494,656	49.56%
14000	459,898,880	223,096,832	48.51%
15000	485,351,424	231,702,528	47.74%
16000	512,176,128	241,451,008	47.14%
16827	534,540,288	249,696,256	46.71%

Memory profile (before the patch)

   191    509.6 MiB      1.4 MiB                       cset = self.repos.get_changeset(next_youngest)
   192    509.6 MiB      0.0 MiB                       try:
   193                                                     # steps 1. and 2.
   194    509.6 MiB    384.9 MiB                           self._insert_changeset(db, next_youngest, cset)
   195                                                 except Exception, e: # *another* 1.1. resync attempt won
   196                                                     if isinstance(e, self.env.db_exc.IntegrityError):
   197                                                         self.log.warning("Revision %s in '%s' already "
   198                                                                          "cached: %r", next_youngest,
   199                                                                          _norm_reponame(self), e)

Memory profile (after the patch)

   191    238.3 MiB      3.4 MiB                       cset = self.repos.get_changeset(next_youngest)
   192    238.3 MiB      0.0 MiB                       try:
   193                                                     # steps 1. and 2.
   194    238.3 MiB    121.6 MiB                           self._insert_changeset(db, next_youngest, cset)
   195                                                 except Exception, e: # *another* 1.1. resync attempt won
   196                                                     if isinstance(e, self.env.db_exc.IntegrityError):
   197                                                         self.log.warning("Revision %s in '%s' already "
   198                                                                          "cached: %r", next_youngest,
   199                                                                          _norm_reponame(self), e)