view tests/test-exchange-obsmarkers-case-B5.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.

============================================
Testing obsolescence markers push: Cases B.5
============================================

Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).

This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.

Category B: pruning case
TestCase 5: Push of a children of changeset which successors is pruned

B.5 Push of a children of changeset which successors is pruned
==============================================================

.. This case Mirror A.4, with pruned changeset successors.
..
.. {{{
..   C ◔
..     |
..   B⇠ø⇠⊗ B'
..     | |
..   A ø⇠○ A'
..     |/
..     ●
.. }}}
..
.. Marker exist from:
..
..  * `A ø⇠○ A'`
..  * `B ø⇠○ B'`
..  * chain from B
..  * `B' is pruned`
..
.. Command run:
..
..  * hg push -r C
..
.. Expected exchange:
..
..  * chain from B
..
.. Expected exclude:
..
..  * `A ø⇠○ A'`
..  * `B ø⇠○ B'`
..  * `B' prune`

Setup
-----

  $ . $TESTDIR/testlib/exchange-obsmarker-util.sh

initial

  $ setuprepos B.5
  creating test repo for test case B.5
  - pulldest
  - main
  - pushdest
  cd into `main` and proceed with env setup
  $ cd main
  $ mkcommit A0
  $ mkcommit B0
  $ mkcommit C
  $ hg up --quiet 0
  $ mkcommit A1
  created new head
  $ mkcommit B1
  $ hg debugobsolete --hidden `getid 'desc(A0)'` `getid 'desc(A1)'`
  1 new obsolescence markers
  obsoleted 1 changesets
  2 new orphan changesets
  $ hg debugobsolete --hidden aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa `getid 'desc(B0)'`
  1 new obsolescence markers
  $ hg debugobsolete --hidden `getid 'desc(B0)'` `getid 'desc(B1)'`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg prune -qd '0 0' 'desc(B1)'
  $ hg log -G --hidden
  x  069b05c3876d (draft): B1
  |
  @  e5ea8f9c7314 (draft): A1
  |
  | *  1d0f3cd25300 (draft): C
  | |
  | x  6e72f0a95b5e (draft): B0
  | |
  | x  28b51eb45704 (draft): A0
  |/
  o  a9bdc8b26820 (public): O
  
  $ inspect_obsmarkers
  obsstore content
  ================
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  069b05c3876d56f62895e853a501ea58ea85f68d 0 {e5ea8f9c73143125d36658e90ef70c6d2027a5b7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  $ cd ..
  $ cd ..

Actual Test (explicit push version)
-----------------------------------

  $ dotest B.5 C -f
  ## Running testcase B.5
  # testing echange of "C" (1d0f3cd25300)
  ## initial state
  # obstore: main
  069b05c3876d56f62895e853a501ea58ea85f68d 0 {e5ea8f9c73143125d36658e90ef70c6d2027a5b7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  # obstore: pulldest
  ## pushing "C" from main to pushdest
  pushing to pushdest
  searching for changes
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 3 changesets with 3 changes to 3 files
  remote: 1 new obsolescence markers
  ## post push state
  # obstore: main
  069b05c3876d56f62895e853a501ea58ea85f68d 0 {e5ea8f9c73143125d36658e90ef70c6d2027a5b7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  ## pulling "1d0f3cd25300" from main into pulldest
  pulling from main
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 3 files
  1 new obsolescence markers
  new changesets 28b51eb45704:1d0f3cd25300 (3 drafts)
  (run 'hg update' to get a working copy)
  ## post pull state
  # obstore: main
  069b05c3876d56f62895e853a501ea58ea85f68d 0 {e5ea8f9c73143125d36658e90ef70c6d2027a5b7} (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 069b05c3876d56f62895e853a501ea58ea85f68d 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pushdest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
  # obstore: pulldest
  aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa 6e72f0a95b5e01a7504743aa941f69cb1fbef8b0 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}