Calling os.fork() at Python exit logs: AttributeError: 'NoneType' object has no attribute '_at_fork_reinit'

[vstinner]

BPO	42350
Nosy	@vstinner, @miss-islington
PRs	bpo-42350: Fix Thread._reset_internal_locks() #23268 [3.9] bpo-42350: Fix Thread._reset_internal_locks() (GH-23268) #23315

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

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2020-11-16.15:18:33.276>
created_at = <Date 2020-11-13.17:51:36.075>
labels = ['library', '3.9', '3.10']
title = "Calling os.fork() at Python exit logs: AttributeError: 'NoneType' object has no attribute '_at_fork_reinit'"
updated_at = <Date 2020-11-16.15:18:33.275>
user = 'https://github.com/vstinner'

bugs.python.org fields:

activity = <Date 2020-11-16.15:18:33.275>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-11-16.15:18:33.276>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2020-11-13.17:51:36.075>
creator = 'vstinner'
dependencies = []
files = []
hgrepos = []
issue_num = 42350
keywords = ['patch']
message_count = 3.0
messages = ['380912', '381099', '381109']
nosy_count = 2.0
nosy_names = ['vstinner', 'miss-islington']
pr_nums = ['23268', '23315']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue42350'
versions = ['Python 3.9', 'Python 3.10']

[vstinner]

The following code logs an error:
---

Exception ignored in: <function _after_fork at 0x7f2bf3b057e0>
Traceback (most recent call last):
  File "/home/vstinner/python/master/Lib/threading.py", line 1508, in _after_fork
    thread._reset_internal_locks(True)
  File "/home/vstinner/python/master/Lib/threading.py", line 847, in _reset_internal_locks
    self._tstate_lock._at_fork_reinit()
AttributeError: 'NoneType' object has no attribute '_at_fork_reinit'

---

Code:
---

#!/usr/bin/python3
import atexit
import subprocess


def preexec():
    pass


def exit_handler():
    proc = subprocess.Popen(
        ["pwd"],
        preexec_fn=preexec,
    )
    proc.communicate()


if __name__ == "__main__":
    atexit.register(exit_handler)

---

It is a regression caused by the following bpo-40089 fix:

commit 87255be
Author: Victor Stinner <vstinner@python.org>
Date: Tue Apr 7 23:11:49 2020 +0200

bpo-40089: Add _at_fork_reinit() method to locks (GH-19195)

[vstinner]

New changeset 5909a49 by Victor Stinner in branch 'master':
bpo-42350: Fix Thread._reset_internal_locks() (GH-23268)
5909a49

[miss-islington]

New changeset cf70854 by Miss Islington (bot) in branch '3.9':
bpo-42350: Fix Thread._reset_internal_locks() (GH-23268)
cf70854