New submission from STINNER Victor <victor.stin...@haypocalc.com>:
test_io.check_interrupted_write() has two threads and a pipe:
- reader (thread): read one byte from the pipe
- writer (main thread): write 1 MB into the pipe
An alarm (SIGALRM) is scheduled in one second. The writer blocks because the
pipe buffer is smaller than 1 MB, but it is supposed to fill the pipe. The
reader is supposed to exit quickly: the writer wrote a least one byte.
The test fails *sometimes* on FreeBSD 6:
[ 85/352] test_io
Exception in thread Thread-274:
Traceback (most recent call last):
File "/usr/home/db3l/buildarea/3.2.bolen-freebsd/build/Lib/threading.py",
line 736, in _bootstrap_inner
self.run()
File "/usr/home/db3l/buildarea/3.2.bolen-freebsd/build/Lib/threading.py",
line 689, in run
self._target(*self._args, **self._kwargs)
File "/usr/home/db3l/buildarea/3.2.bolen-freebsd/build/Lib/test/test_io.py",
line 2660, in _read
s = os.read(r, 1)
OSError: [Errno 4] Interrupted system call
It is a race condition, this buildbot is very slow. The reader has maybe not
enough time to read 1 byte.
The test was fixed in Python 3.3 (#11859) by adding pthread_sigmask() (issue
#8407) and using it in the test: commit 28b9702a83d1.
The problem looks to be specific of FreeBSD 6 and 7 (according to #11859). The
easiest solution is to skip the test on these platforms.
To workaround the lack of pthread_sigmark(), we can use two processes instead
of two threads. But it is maybe too much work just to fix a bug in a test (the
bug is not in Python).
----------
components: IO, Tests
messages: 139355
nosy: haypo, neologix
priority: normal
severity: normal
status: open
title: test_io.check_interrupted_write() sporadic failures on FreeBSD 6 on
Python 2.7/3.2
versions: Python 2.7, Python 3.2
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue12429>
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