view tests/test-convert-svn-encoding.t @ 47010:76ae43d5b1db stable

repoview: fix memory leak of filtered repo classes

The leak occurs in long-running server processes with
extensions, and is measured at 110kB per request.

Before this change, the contents of the `_filteredrepotypes`
cache are not properly garbage collected, despite it begin
a `WeakKeyDictionary`.

Extensions have a tendency to generate a new repository class
for each `localrepo` instantiation. Server processes based
on `hgwebdir_mod` will instantiate a new `localrepo` for each
HTTP request that involves a repository.

As a result, with a testing process that repeatedly opens a
repository with several extensions activated
(`topic` notably among them), we see a steady increase in
resident memory of 110kB per repository instantiation before this
change. This is also true, if we call `gc.collect()` at each
instantiation, like `hgwebdir_mod` does, or not.

The cause of the leak is that the *values* aren't weak references.
This change uses `weakref.ref` for the values, and this makes
in our measurements the resident size increase drop to 5kB per
repository instantiation, with no explicit call of `gc.collect()`
at all.
There is currently no reason to believe that this remaining leak
of 5kB is related to or even due to Mercurial core.

We've also seen evidence that `ui.ui` instances weren't properly
garbage collected before the change (with the change, they are).
This could explain why the figures are relatively high.

In theory, the collection of weak references could lead to
much more misses in the cache, so we measured the impact on
the original case that was motivation for introducing that cache
in 7e89bd0cfb86 (see also issue5043): `hg convert` of the
mozilla-central repository. The bad news here is that there is a
major memory leak there, both with and without the present changeset.
There were no more cache misses, and we could see no
more memory leak with this change: the resident size after importing
roughly 100000 changesets was at 12.4GB before, and 12.5GB after.
The small increase is mentioned for completeness only, and we
believe that it should be ignored, at least as long as the main
leak isn't fixed. At less than 1% of the main leak, even finding out
whether it is merely noise would be wasteful.

Original context where this was spotted and first mitigated:
  https://foss.heptapod.net/heptapod/heptapod/-/issues/466

The leak reduction was also obtained in Heptapod inner HTTP server,
which amounts to the same as `hgwebdir_mod` for these questions.

The measurements done with Python 3.9, similar figures seen with 3.8.
More work on our side would be needed to give measurements with 2.7,
because of testing server process does not support it.

#require svn svn-bindings

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert =
  > EOF

  $ svnadmin create svn-repo
  $ svnadmin load -q svn-repo < "$TESTDIR/svn/encoding.svndump"

Convert while testing all possible outputs

  $ hg --debug convert svn-repo A-hg --config progress.debug=1
  initializing destination A-hg repository
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  run hg sink pre-conversion action
  scanning source...
  found trunk at 'trunk'
  found tags at 'tags'
  found branches at 'branches'
  found branch branch\xc3\xa9 at 5 (esc)
  found branch branch\xc3\xa9e at 6 (esc)
  scanning: 1/4 revisions (25.00%)
  reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
  fetching revision log for "/trunk" from 4 to 0
  parsing revision 4 (2 changes)
  parsing revision 3 (4 changes)
  parsing revision 2 (3 changes)
  parsing revision 1 (3 changes)
  no copyfrom path, don't know what to do.
  '/branches' is not under '/trunk', ignoring
  '/tags' is not under '/trunk', ignoring
  scanning: 2/4 revisions (50.00%)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9 (glob)
  fetching revision log for "/branches/branch\xc3\xa9" from 5 to 0 (esc)
  parsing revision 5 (1 changes)
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9 (glob)
  found parent of branch /branches/branch\xc3\xa9 at 4: /trunk (esc)
  scanning: 3/4 revisions (75.00%)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
  fetching revision log for "/branches/branch\xc3\xa9e" from 6 to 0 (esc)
  parsing revision 6 (1 changes)
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
  found parent of branch /branches/branch\xc3\xa9e at 5: /branches/branch\xc3\xa9 (esc)
  scanning: 4/4 revisions (100.00%)
  scanning: 5/4 revisions (125.00%)
  scanning: 6/4 revisions (150.00%)
  sorting...
  converting...
  5 init projA
  source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@1
  converting: 0/6 revisions (0.00%)
  reusing manifest from p1 (no file change)
  committing changelog
  updating the branch cache
  4 hello
  source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@2
  converting: 1/6 revisions (16.67%)
  reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
  scanning paths: /trunk/\xc3\xa0 0/3 paths (0.00%) (esc)
  scanning paths: /trunk/\xc3\xa0/e\xcc\x81 1/3 paths (33.33%) (esc)
  scanning paths: /trunk/\xc3\xa9 2/3 paths (66.67%) (esc)
  committing files:
  \xc3\xa0/e\xcc\x81 (esc)
  getting files: \xc3\xa0/e\xcc\x81 1/2 files (50.00%) (esc)
  \xc3\xa9 (esc)
  getting files: \xc3\xa9 2/2 files (100.00%) (esc)
  committing manifest
  committing changelog
  updating the branch cache
  3 copy files
  source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@3
  converting: 2/6 revisions (33.33%)
  scanning paths: /trunk/\xc3\xa0 0/4 paths (0.00%) (esc)
  gone from -1
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
  scanning paths: /trunk/\xc3\xa8 1/4 paths (25.00%) (esc)
  copied to \xc3\xa8 from \xc3\xa9@2 (esc)
  scanning paths: /trunk/\xc3\xa9 2/4 paths (50.00%) (esc)
  gone from -1
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
  scanning paths: /trunk/\xc3\xb9 3/4 paths (75.00%) (esc)
  mark /trunk/\xc3\xb9 came from \xc3\xa0:2 (esc)
  getting files: \xc3\xa0/e\xcc\x81 1/4 files (25.00%) (esc)
  getting files: \xc3\xa9 2/4 files (50.00%) (esc)
  committing files:
  \xc3\xa8 (esc)
  getting files: \xc3\xa8 3/4 files (75.00%) (esc)
   \xc3\xa8: copy \xc3\xa9:6b67ccefd5ce6de77e7ead4f5292843a0255329f (esc)
  \xc3\xb9/e\xcc\x81 (esc)
  getting files: \xc3\xb9/e\xcc\x81 4/4 files (100.00%) (esc)
   \xc3\xb9/e\xcc\x81: copy \xc3\xa0/e\xcc\x81:a9092a3d84a37b9993b5c73576f6de29b7ea50f6 (esc)
  committing manifest
  committing changelog
  updating the branch cache
  2 remove files
  source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/trunk@4
  converting: 3/6 revisions (50.00%)
  scanning paths: /trunk/\xc3\xa8 0/2 paths (0.00%) (esc)
  gone from -1
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
  scanning paths: /trunk/\xc3\xb9 1/2 paths (50.00%) (esc)
  gone from -1
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/trunk (glob)
  getting files: \xc3\xa8 1/2 files (50.00%) (esc)
  getting files: \xc3\xb9/e\xcc\x81 2/2 files (100.00%) (esc)
  committing files:
  committing manifest
  committing changelog
  updating the branch cache
  1 branch to branch?
  source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/branches/branch?@5
  converting: 4/6 revisions (66.67%)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9 (glob)
  scanning paths: /branches/branch\xc3\xa9 0/1 paths (0.00%) (esc)
  reusing manifest from p1 (no file change)
  committing changelog
  updating the branch cache
  0 branch to branch?e
  source: svn:afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af/branches/branch?e@6
  converting: 5/6 revisions (83.33%)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
  scanning paths: /branches/branch\xc3\xa9e 0/1 paths (0.00%) (esc)
  reusing manifest from p1 (no file change)
  committing changelog
  updating the branch cache
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
  reparent to file:/*/$TESTTMP/svn-repo (glob)
  reparent to file:/*/$TESTTMP/svn-repo/branches/branch%C3%A9e (glob)
  updating tags
  committing files:
  .hgtags
  committing manifest
  committing changelog
  updating the branch cache
  run hg sink post-conversion action
  $ cd A-hg
  $ hg up
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Check tags are in UTF-8

  $ cat .hgtags
  e94e4422020e715add80525e8f0f46c9968689f1 branch\xc3\xa9e (esc)
  f7e66f98380ed1e53a797c5c7a7a2616a7ab377d branch\xc3\xa9 (esc)

  $ cd ..

Subversion sources don't support non-ASCII characters in HTTP(S) URLs.

  $ XFF=$($PYTHON -c 'from mercurial.utils.procutil import stdout; stdout.write(b"\xff")')
  $ hg convert --source-type=svn http://localhost:$HGPORT/$XFF test
  initializing destination test repository
  Subversion sources don't support non-ASCII characters in HTTP(S) URLs. Please percent-encode them.
  http://localhost:$HGPORT/\xff does not look like a Subversion repository (esc)
  abort: http://localhost:$HGPORT/\xff: missing or unsupported repository (esc)
  [255]

In Subversion, paths are Unicode (encoded as UTF-8). Therefore paths that can't
be converted between UTF-8 and the locale encoding (which is always ASCII in
tests) don't work.

  $ cp -R svn-repo $XFF
  $ hg convert $XFF test
  initializing destination test repository
  Subversion requires that paths can be converted to Unicode using the current locale encoding (ascii)
  \xff does not look like a CVS checkout (glob) (esc)
  $TESTTMP/\xff does not look like a Git repository (esc)
  \xff does not look like a Subversion repository (glob) (esc)
  \xff is not a local Mercurial repository (glob) (esc)
  \xff does not look like a darcs repository (glob) (esc)
  \xff does not look like a monotone repository (glob) (esc)
  \xff does not look like a GNU Arch repository (glob) (esc)
  \xff does not look like a Bazaar repository (glob) (esc)
  cannot find required "p4" tool
  abort: \xff: missing or unsupported repository (glob) (esc)
  [255]
  $ hg convert file://$TESTTMP/$XFF test
  initializing destination test repository
  Subversion requires that file URLs can be converted to Unicode using the current locale encoding (ascii)
  file:/*/$TESTTMP/\xff does not look like a CVS checkout (glob) (esc)
  $TESTTMP/file:$TESTTMP/\xff does not look like a Git repository (esc)
  file:/*/$TESTTMP/\xff does not look like a Subversion repository (glob) (esc)
  file:/*/$TESTTMP/\xff is not a local Mercurial repository (glob) (esc)
  file:/*/$TESTTMP/\xff does not look like a darcs repository (glob) (esc)
  file:/*/$TESTTMP/\xff does not look like a monotone repository (glob) (esc)
  file:/*/$TESTTMP/\xff does not look like a GNU Arch repository (glob) (esc)
  file:/*/$TESTTMP/\xff does not look like a Bazaar repository (glob) (esc)
  file:/*/$TESTTMP/\xff does not look like a P4 repository (glob) (esc)
  abort: file:/*/$TESTTMP/\xff: missing or unsupported repository (glob) (esc)
  [255]

Subversion decodes percent-encoded bytes on the converted, UTF-8-encoded
string. Therefore, if the percent-encoded bytes aren't valid UTF-8, Subversion
would choke on them when converting them to the locale encoding.

  $ hg convert file://$TESTTMP/%FF test
  initializing destination test repository
  Subversion does not support non-UTF-8 percent-encoded bytes in file URLs
  file:/*/$TESTTMP/%FF does not look like a CVS checkout (glob)
  $TESTTMP/file:$TESTTMP/%FF does not look like a Git repository
  file:/*/$TESTTMP/%FF does not look like a Subversion repository (glob)
  file:/*/$TESTTMP/%FF is not a local Mercurial repository (glob)
  file:/*/$TESTTMP/%FF does not look like a darcs repository (glob)
  file:/*/$TESTTMP/%FF does not look like a monotone repository (glob)
  file:/*/$TESTTMP/%FF does not look like a GNU Arch repository (glob)
  file:/*/$TESTTMP/%FF does not look like a Bazaar repository (glob)
  file:/*/$TESTTMP/%FF does not look like a P4 repository (glob)
  abort: file:/*/$TESTTMP/%FF: missing or unsupported repository (glob)
  [255]