Debugging segmentation faults

[George Sakkis]

I have a pure python program (no C extensions) that occasionally core
dumps in a non-reproducible way. The program is started by a (non-
python) cgi script when a form is submitted. It involves running a
bunch of other programs through subprocess in multiple threads and
writing its output in several files. So the only suspicious parts I
can think of is subprocess and/or multithreading. For the
multithreading part I'm using a modified version of threadpool.py
(http://www.chrisarndt.de/en/software/python/threadpool/), which is
built on top of the threading and Queue stdlib modules. Whatever bugs
may linger there, I'd hope that they would show up as normal Python
exceptions instead of segfaults.

All I have now is a few not particularly insightful core files (actual
path names and args changed for privacy):

/home/gsakkis/foo>gdb --core core.20140
GNU gdb Red Hat Linux (5.2-2)
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and
you are
welcome to change it and/or distribute copies of it under certain
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for
details.
This GDB was configured as "i386-redhat-linux".
Core was generated by `python2.5 /home/gsakkis/foo/foo.py --XXX --
max=30 --bar=/tmp/83840`
Program terminated with signal 11, Segmentation fault.
#0  0x080b222d in ?? ()
(gdb) backtrace
#0  0x080b222d in ?? ()
#1  0x080b28d1 in ?? ()
#2  0x080fa8ab in ?? ()
#3  0x0805c918 in ?? ()
(...)
#28 0x080b310f in ?? ()
#29 0x080dbfdd in ?? ()
#30 0x40021fef in ?? ()

Any hints ?