[capi-sig] Python segfaulting on exit

Aaron Staley astaley at berkeley.edu
Sat Feb 7 04:09:48 CET 2009

M.-A. Lemburg wrote:
> On 2009-02-06 12:18, Aaron Staley wrote:
>> Recently (I suspect after I upgraded to Ubuntu Intrepid), python has
>> been segfaulting whenever it exits AND my Cpp extension has been importing.
>> The exact error (from valgrind is):
>> ==11326== Process terminating with default action of signal 11 (SIGSEGV)
>> ==11326==  Access not within mapped region at address 0x40
>> ==11326==    at 0x5BAF974: (within /lib/libselinux.so.1)
>> ==11326==    by 0x5BA8B8D: (within /lib/libselinux.so.1)
>> ==11326==    by 0x5BA11D7: (within /lib/libselinux.so.1)
>> ==11326==    by 0x5BB134F: (within /lib/libselinux.so.1)
>> ==11326==    by 0x400E152: (within /lib/ld-2.8.90.so)
>> ==11326==    by 0x40B6D68: exit (in /lib/tls/i686/cmov/libc-2.8.90.so)
>> ==11326==    by 0x80ED204: handle_system_exit (pythonrun.c:1620)
>> ==11326==    by 0x80ED3FC: PyErr_PrintEx (pythonrun.c:1064)
>> ==11326==    by 0x80ED661: PyErr_Print (pythonrun.c:978)
>> ==11326==    by 0x80EDC87: PyRun_InteractiveOneFlags (pythonrun.c:795)
>> ==11326==    by 0x80EDDB7: PyRun_InteractiveLoopFlags (pythonrun.c:723)
>> ==11326==    by 0x80EE515: PyRun_AnyFileExFlags (pythonrun.c:692)
>> Has anyone seen this before? This is not a showstopper for me, but it is
>> a bit annoying.
> This typically happens in case of a refcount bug in your extension.
> Python finalizes all modules before exiting and during the course
> of this, clears all module dictionaries.
> It's also possible that the cleanup process triggers an exception
> which cannot be handled properly anymore during exit due to a
> half-gone Python interpreter system.
Thanks for the tips.

I actually forgot to mention that just importing the extension will 
trigger the crashing behavior when I exit; I do not even need to call 
module functions.  Correct me if I'm wrong, but it doesn't seem that a 
module import should be affecting any reference counts.

I should note that my module is linking to shared libraries (namely 
opencv) when linked; has this been known to have issues?

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