NetBSD: do not use POSIX semaphores

[0-wiz-0]

BPO	46045
Nosy	@0-wiz-0, @serhiy-storchaka
PRs	bpo-46045: Do not use POSIX semaphores on NetBSD #30047

^{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 = None
created_at = <Date 2021-12-11.10:31:04.604>
labels = ['interpreter-core', 'type-bug', '3.11']
title = 'NetBSD: do not use POSIX semaphores'
updated_at = <Date 2022-01-18.22:48:10.053>
user = 'https://github.com/0-wiz-0'

bugs.python.org fields:

activity = <Date 2022-01-18.22:48:10.053>
actor = 'wiz'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2021-12-11.10:31:04.604>
creator = 'wiz'
dependencies = []
files = []
hgrepos = []
issue_num = 46045
keywords = ['patch']
message_count = 4.0
messages = ['408291', '410581', '410888', '410910']
nosy_count = 2.0
nosy_names = ['wiz', 'serhiy.storchaka']
pr_nums = ['30047']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue46045'
versions = ['Python 3.11']

[0-wiz-0]

On NetBSD by default, the following tests do not finish in > 1h:

1:07:13 load avg: 0.00 running: test_compileall (1 hour 7 min), test_multiprocessing_fork (1 hour 7 min), test_concurrent_futures (1 hour 6 min)

Defining HAVE_BROKEN_POSIX_SEMAPHORES fixes this, and they finish:

0:00:32 load avg: 10.63 [408/427/17] test_compileall passed ...
...
0:02:37 load avg: 3.04 [427/427/22] test_concurrent_futures passed (2 min 33 sec)

The last one fails:
test_multiprocessing_fork

with most of the subtests failing like this:

ERROR: test_shared_memory_SharedMemoryServer_ignores_sigint (test.test_multiprocessing_fork.WithProcessesTestSharedMemory)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "/scratch/lang/python310/work/Python-3.10.1/Lib/test/_test_multiprocessing.py", line 4006, in test_shared_memory_SharedMemoryServer_ignores_sigint
    sl = smm.ShareableList(range(10))
  File "/scratch/lang/python310/work/Python-3.10.1/Lib/multiprocessing/managers.py", line 1372, in ShareableList
    sl = shared_memory.ShareableList(sequence)
  File "/scratch/lang/python310/work/Python-3.10.1/Lib/multiprocessing/shared_memory.py", line 327, in __init__
    self.shm = SharedMemory(name, create=True, size=requested_size)
  File "/scratch/lang/python310/work/Python-3.10.1/Lib/multiprocessing/shared_memory.py", line 92, in __init__
    self._fd = _posixshmem.shm_open(
OSError: [Errno 86] Not supported: '/psm_b1ec903a'

I think this is a separate issue, so I'd like to define HAVE_BROKEN_POSIX_SEMAPHORES for now.

This has been done in pkgsrc since at least python 2.7 (in 2011), I haven't dug deeper.

[0-wiz-0]

ping - this patch needs a review

[serhiy-storchaka]

New changeset 60ceedb by Thomas Klausner in branch 'main':
bpo-46045: Do not use POSIX semaphores on NetBSD (GH-30047)
60ceedb

[0-wiz-0]

Thanks for merging this, @serhiy.storchaka!

[kumaraditya303]

Fixed by #30047