STINNER Victor <victor.stin...@haypocalc.com> added the comment:
> Since the commit c9207c6ce24a, test_signal fails on OpenIndiana:
>
> http://www.python.org/dev/buildbot/all/builders/x86%20OpenIndiana%203.x/builds/1179
> ======================================================================
> ERROR: test_block_unlock (test.test_signal.PthreadSigmaskTests)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
> File
> "/export/home/buildbot/64bits/3.x.cea-indiana-amd64/build/Lib/test/test_signal.py",
> line 539, in test_block_unlock
> self.assertEqual(set(old_mask) ^ set(blocked), {signum})
> File
> "/export/home/buildbot/64bits/3.x.cea-indiana-amd64/build/Lib/test/test_signal.py",
> line 501, in handler
> 1/0
> ZeroDivisionError: division by zero
This is because a thread different than the main thread receives the
signal and calls the signal handler. Antoine found that "python -m
test_pydoc test_signal" is enough to reproduce the problem (on any OS,
or at least on Linux). test_pydoc loads a lot (all?) of Python modules
including _tkinter, and _tkinter (libtcl) creates a C thread which waits
events using select().
I see 3 solutions:
a) Use pthread_kill() to send the signal directly to the right thread
(the main thread)
b) Destroy _tkinter: Tcl_Finalize() exits the thread, but this function
is never called. _tkinter.c contains the following code:
#if 0
/* This was not a good idea; through <Destroy> bindings,
Tcl_Finalize() may invoke Python code but at that point the
interpreter and thread state have already been destroyed! */
Py_AtExit(Tcl_Finalize);
#endif
c) Skip the test if the _tkinter thread is present. Check if the
_tkinter module is loaded *should* be enough to check if the Tcl thread
is running. Unload the _tkinter module is not possible: modules written
in C cannot be unloaded. But it is possible to remove all references
from the Python object space, so check >'_tkinter' in sys.modules< is
maybe not reliable.
I don't know if some platforms have pthread_sigmask() but not
pthread_kill().
I have a patch to expose pthread_kill(), sigpending() and sigwait(). I
will publish it tomorrow for a review.
--
test_signal doesn't fail on all platforms. Possible reasons:
- the platform doesn't have pthread_sigmask(), and so the test is
skipped
- the libtcl version is different, a newer version masks maybe signals?
- (unlikely!) os.kill() always sends the signal to the main thread
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue8407>
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