various refleaks when calling the __init__() method of an object more than once

[orenmn]

BPO	31787
Nosy	@rhettinger, @vstinner, @methane, @orenmn, @csabella, @miss-islington
PRs	bpo-31787: Prevent refleaks when calling __init__() more than once #3995 [3.7] bpo-31787: Prevent refleaks when calling __init__() more than once (GH-3995) #5657 [3.6] bpo-31787: Prevent refleaks when calling __init__() more than once (GH-3995) #5659 bpo-31787: Skip refleak check when _hashlib is not available #5660 [3.7] bpo-31787: Skip refleak check when _hashlib is not available (GH-5660) #5661 [3.6] bpo-31787: Skip refleak check when _hashlib is not available (GH-5660) #5662

^{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 2018-02-13.13:15:49.506>
created_at = <Date 2017-10-14.09:16:28.394>
labels = ['extension-modules', '3.7', '3.8', 'performance']
title = 'various refleaks when calling the __init__() method of an object more than once'
updated_at = <Date 2018-06-20.16:00:04.996>
user = 'https://github.com/orenmn'

bugs.python.org fields:

activity = <Date 2018-06-20.16:00:04.996>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2018-02-13.13:15:49.506>
closer = 'methane'
components = ['Extension Modules']
creation = <Date 2017-10-14.09:16:28.394>
creator = 'Oren Milman'
dependencies = []
files = []
hgrepos = []
issue_num = 31787
keywords = ['patch']
message_count = 9.0
messages = ['304389', '310387', '312113', '312116', '312118', '312124', '312126', '312128', '320088']
nosy_count = 6.0
nosy_names = ['rhettinger', 'vstinner', 'methane', 'Oren Milman', 'cheryl.sabella', 'miss-islington']
pr_nums = ['3995', '5657', '5659', '5660', '5661', '5662']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'resource usage'
url = 'https://bugs.python.org/issue31787'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']

[orenmn]

Various init() methods don't decref (if needed) before assigning to fields
of the object's struct (i.e. assigning to self->some_field):

• _asyncio_Task___init___impl() (in Modules/_asynciomodule.c)
• _lzma_LZMADecompressor___init___impl() (in Modules/_lzmamodule.c)
• _bz2_BZ2Decompressor___init___impl() (in Modules/_bz2module.c)
• EVP_tp_init() (in Modules/_hashopenssl.c)
• property_init_impl() (in Objects/descrobject.c)
• cm_init() (in Objects/funcobject.c)
• sm_init() (in Objects/funcobject.c)

For example, _asyncio_Task___init___impl() does self->task_coro = coro;
instead of Py_XSETREF(self->task_coro, coro);.
Thus, the following code would result in at least one refleak:
import _asyncio
task = _asyncio.Task('foo')
task.init('foo')

I would open a PR to fix this soon.

[csabella]

Raymond,

You approved this PR pending some test cases. Would you have the chance to take another look?

Thanks!

Oren, it looks like you'll need to rebase before this could be merged.

[methane]

New changeset d019bc8 by INADA Naoki (Oren Milman) in branch 'master':
bpo-31787: Prevent refleaks when calling __init__() more than once (GH-3995)
d019bc8

[miss-islington]

New changeset ef20abe by Miss Islington (bot) in branch '3.7':
bpo-31787: Prevent refleaks when calling __init__() more than once (GH-3995)
ef20abe

[methane]

New changeset 4731634 by INADA Naoki in branch '3.6':
bpo-31787: Prevent refleaks when calling __init__() more than once (GH-3995)
4731634

[methane]

New changeset f0bc645 by INADA Naoki in branch 'master':
bpo-31787: Skip refleak check when _hashlib is not available (GH-5660)
f0bc645

[miss-islington]

New changeset e81a6c8 by Miss Islington (bot) in branch '3.7':
bpo-31787: Skip refleak check when _hashlib is not available (GH-5660)
e81a6c8

[miss-islington]

New changeset 5d0d0ea by Miss Islington (bot) in branch '3.6':
bpo-31787: Skip refleak check when _hashlib is not available (GH-5660)
5d0d0ea

[vstinner]

It seems like the lzma fix is incomplete: bpo-33916, "test_lzma: test_refleaks_in_decompressor___init__() leaks 100 handles on Windows".