view tests/test-releasenotes-merging.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 fuzzywuzzy

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

  $ hg init simple-repo
  $ cd simple-repo

A fix directive from commit message is added to release notes

  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix::
  > 
  >    Fix from commit message.
  > EOF

  $ cat >> $TESTTMP/single-fix-bullet << EOF
  > Bug Fixes
  > =========
  > 
  > * Fix from release notes.
  > EOF

  $ hg releasenotes -r . $TESTTMP/single-fix-bullet

  $ cat $TESTTMP/single-fix-bullet
  Bug Fixes
  =========
  
  * Fix from release notes.
  
  * Fix from commit message.

Processing again ignores the already added bullet.

  $ hg releasenotes -r . $TESTTMP/single-fix-bullet

  $ cat $TESTTMP/single-fix-bullet
  Bug Fixes
  =========
  
  * Fix from release notes.
  
  * Fix from commit message.

  $ cd ..

Sections are unioned

  $ hg init subsections
  $ cd subsections
  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > Commit 1
  > 
  > .. feature:: Commit Message Feature
  > 
  >    This describes a feature from a commit message.
  > EOF

  $ cat >> $TESTTMP/single-feature-section << EOF
  > New Features
  > ============
  > 
  > Notes Feature
  > -------------
  > 
  > This describes a feature from a release notes file.
  > EOF

  $ hg releasenotes -r . $TESTTMP/single-feature-section

  $ cat $TESTTMP/single-feature-section
  New Features
  ============
  
  Notes Feature
  -------------
  
  This describes a feature from a release notes file.
  
  Commit Message Feature
  ----------------------
  
  This describes a feature from a commit message.

Doing it again won't add another section

  $ hg releasenotes -r . $TESTTMP/single-feature-section
  Commit Message Feature already exists in feature section; ignoring

  $ cat $TESTTMP/single-feature-section
  New Features
  ============
  
  Notes Feature
  -------------
  
  This describes a feature from a release notes file.
  
  Commit Message Feature
  ----------------------
  
  This describes a feature from a commit message.

  $ cd ..

Bullets from rev merge with those from notes file.

  $ hg init bullets
  $ cd bullets
  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix::
  > 
  >    this is fix1.
  > EOF

  $ touch fix2
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. fix::
  > 
  >    this is fix2.
  > EOF

  $ hg releasenotes -r 'all()' $TESTTMP/relnotes-bullet-problem
  $ cat $TESTTMP/relnotes-bullet-problem
  Bug Fixes
  =========
  
  * this is fix1.
  
  * this is fix2.
  $ touch fix3
  $ hg -q commit -A -l - << EOF
  > commit 3
  > 
  > .. fix::
  > 
  >    this is fix3.
  > EOF

  $ hg releasenotes -r . $TESTTMP/relnotes-bullet-problem
  $ cat $TESTTMP/relnotes-bullet-problem
  Bug Fixes
  =========
  
  * this is fix1.
  
  * this is fix2.
  
  * this is fix3.

  $ cd ..

Ignores commit messages containing issueNNNN based on issue number.

  $ hg init simple-fuzzrepo
  $ cd simple-fuzzrepo
  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix::
  > 
  >    Resolved issue4567.
  > EOF

  $ cat >> $TESTTMP/issue-number-notes << EOF
  > Bug Fixes
  > =========
  > 
  > * Fixed issue1234 related to XYZ.
  > 
  > * Fixed issue4567 related to ABC.
  > 
  > * Fixed issue3986 related to PQR.
  > EOF

  $ hg releasenotes -r . $TESTTMP/issue-number-notes
  "issue4567" already exists in notes; ignoring

  $ cat $TESTTMP/issue-number-notes
  Bug Fixes
  =========
  
  * Fixed issue1234 related to XYZ.
  
  * Fixed issue4567 related to ABC.
  
  * Fixed issue3986 related to PQR.

  $ cd ..

Adds short commit messages (words < 10) without
comparison unless there is an exact match.

  $ hg init tempdir
  $ cd tempdir
  $ touch feature1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. feature::
  > 
  >    Adds a new feature 1.
  > EOF

  $ hg releasenotes -r . $TESTTMP/short-sentence-notes

  $ touch feature2
  $ hg -q commit -A -l - << EOF
  > commit 2
  > 
  > .. feature::
  > 
  >    Adds a new feature 2.
  > EOF

  $ hg releasenotes -r . $TESTTMP/short-sentence-notes
  $ cat $TESTTMP/short-sentence-notes
  New Features
  ============
  
  * Adds a new feature 1.
  
  * Adds a new feature 2.

  $ cd ..

Ignores commit messages based on fuzzy comparison.

  $ hg init fuzznotes
  $ cd fuzznotes
  $ touch fix1
  $ hg -q commit -A -l - << EOF
  > commit 1
  > 
  > .. fix::
  > 
  >    This is a fix with another line.
  >    And it is a big one.
  > EOF

  $ cat >> $TESTTMP/fuzz-ignore-notes << EOF
  > Bug Fixes
  > =========
  > 
  > * Fixed issue4567 by improving X.
  > 
  > * This is the first line. This is next line with one newline.
  > 
  >   This is another line written after two newlines. This is going to be a big one.
  > 
  > * This fixes another problem.
  > EOF

  $ hg releasenotes -r . $TESTTMP/fuzz-ignore-notes
  "This is a fix with another line. And it is a big one." already exists in notes file; ignoring

  $ cat $TESTTMP/fuzz-ignore-notes
  Bug Fixes
  =========
  
  * Fixed issue4567 by improving X.
  
  * This is the first line. This is next line with one newline.
  
    This is another line written after two newlines. This is going to be a big
    one.
  
  * This fixes another problem.