test_threading is leaking references

[pablogsal]

BPO	37126
Nosy	@vstinner, @ambv, @pablogsal
PRs	bpo-37126: Allow structseq objects to be tracked by the GC #13729 bpo-37126: Call PyObject_GC_UnTrack in structseq dealloc #13751

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-06-02.21:15:11.918>
created_at = <Date 2019-06-01.17:00:48.642>
labels = ['3.8', 'tests']
title = 'test_threading is leaking references'
updated_at = <Date 2019-06-02.21:15:11.917>
user = 'https://github.com/pablogsal'

bugs.python.org fields:

activity = <Date 2019-06-02.21:15:11.917>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2019-06-02.21:15:11.918>
closer = 'vstinner'
components = ['Tests']
creation = <Date 2019-06-01.17:00:48.642>
creator = 'pablogsal'
dependencies = []
files = []
hgrepos = []
issue_num = 37126
keywords = ['patch']
message_count = 8.0
messages = ['344191', '344195', '344197', '344209', '344289', '344309', '344310', '344320']
nosy_count = 3.0
nosy_names = ['vstinner', 'lukasz.langa', 'pablogsal']
pr_nums = ['13729', '13751']
priority = 'high'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue37126'
versions = ['Python 3.8']

[pablogsal]

https://buildbot.python.org/all/#/builders/1/builds/601

OK (skipped=1)
.
test_threading leaked [9770, 9772, 9768] references, sum=29310
test_threading leaked [3960, 3961, 3959] memory blocks, sum=11880
2 tests failed again:
test_asyncio test_threading

[pablogsal]

❯ ./python -m test test_threading -m test_excepthook_thread_None -R :
Run tests sequentially
0:00:00 load avg: 1.38 [1/1] test_threading
beginning 9 repetitions
123456789
.........
test_threading leaked [364, 364, 364, 364] references, sum=1456
test_threading leaked [164, 164, 164, 164] memory blocks, sum=656
test_threading failed

== Tests result: FAILURE ==

1 test failed:
test_threading

Total duration: 159 ms
Tests result: FAILURE

[pablogsal]

The problem here is that there is a reference cycle with threading.ExceptHookArgs but structseq objects are not tracked by the GC.

[pablogsal]

Łukasz, this PR will fix the x86 Gentoo Refleaks 3.x and friends, so I would recommend landing this before the release.

[pablogsal]

New changeset 7ffcf84 by Pablo Galindo in branch 'master':
bpo-37126: Allow structseq objects to be tracked by the GC (GH-13729)
7ffcf84

[vstinner]

You forgot to call PyObject_GC_UnTrack() in structseq_dealloc(), no?

[pablogsal]

You forgot to call PyObject_GC_UnTrack() in structseq_dealloc(), no?

Yep, thanks for the catch!

[vstinner]

Thanks.

commit 3caf4de
Author: Pablo Galindo <Pablogsal@gmail.com>
Date: Sun Jun 2 21:52:49 2019 +0100

Call PyObject_GC_UnTrack in structseq dealloc (GH-13751)

--

FYI I also fixed test_threading:

commit cdce057
Author: Victor Stinner <vstinner@redhat.com>
Date: Sun Jun 2 23:08:41 2019 +0200

bpo-36829: test_threading: Fix a ref cycle (GH-13752)