test_signal failure

[skrah]

BPO	13084
Nosy	@vstinner, @skrah
Files	check_signum_order.diff

^{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 2011-10-02.17:00:59.618>
created_at = <Date 2011-10-01.09:48:23.037>
labels = ['type-bug', 'tests']
title = 'test_signal failure'
updated_at = <Date 2011-10-02.17:00:59.617>
user = 'https://github.com/skrah'

bugs.python.org fields:

activity = <Date 2011-10-02.17:00:59.617>
actor = 'neologix'
assignee = 'none'
closed = True
closed_date = <Date 2011-10-02.17:00:59.618>
closer = 'neologix'
components = ['Tests']
creation = <Date 2011-10-01.09:48:23.037>
creator = 'skrah'
dependencies = []
files = ['23284']
hgrepos = []
issue_num = 13084
keywords = ['patch']
message_count = 5.0
messages = ['144718', '144720', '144729', '144769', '144775']
nosy_count = 4.0
nosy_names = ['vstinner', 'skrah', 'neologix', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue13084'
versions = ['Python 3.3']

[skrah]

Got this failure on Debian lenny amd64:

[1/1] test_signal
test test_signal failed -- Traceback (most recent call last):
  File "/home/stefan/cpython/Lib/test/test_signal.py", line 339, in test_pending
    """,  *signals)
  File "/home/stefan/cpython/Lib/test/test_signal.py", line 263, in check_wakeup
    assert_python_ok('-c', code)
  File "/home/stefan/cpython/Lib/test/script_helper.py", line 50, in assert_python_ok
    return _assert_python(True, *args, **env_vars)
  File "/home/stefan/cpython/Lib/test/script_helper.py", line 42, in _assert_python
    "stderr follows:\n%s" % (rc, err.decode('ascii', 'ignore')))
AssertionError: Process return code is 1, stderr follows:
Traceback (most recent call last):
  File "<string>", line 41, in <module>
  File "<string>", line 16, in check_signum
Exception: (10, 12) != (12, 10)

1 test failed:
test_signal
[103837 refs]

[neologix]

See http://bugs.python.org/issue12469, specifically http://bugs.python.org/issue12469#msg139831

"""

> When signals are unblocked, pending signal ared delivered in the reverse order
> of their number (also on Linux, not only on FreeBSD 6).

I don't like this.
POSIX doesn't make any guarantee about signal delivery order, except
for real-time signals.
It might work on FreeBSD and Linux, but that's definitely not
documented, and might break with new kernel releases, or other
kernels.

It looks like it works like this on most OSes (Linux, Mac OS X, Solaris,
FreeBSD): I don't see any test_signal failure on 3.x buildbots. If we
have a failure, we can use set() again, but only for test_pending:
signal order should be reliable if signals are not blocked.
"""

Looks like we now have a failure :-)

[vstinner]

WakeupSignalTests.test_pending() doesn't really check our signal handler but more the operating system, especially pthread_sigmask(SIG_UNBLOCK). I don't think that Python should test the signal order delivered by the operating systems when SIG_UNBLOCK.

Anyone motivated to write a patch to use again a set()?

[skrah]

Patch looks good to me (and it fixes the problem).

[python-dev]

New changeset e4f4272479d0 by Charles-François Natali in branch 'default':
Issue bpo-13084: Fix a test_signal failure: the delivery order is only defined for
http://hg.python.org/cpython/rev/e4f4272479d0