| msg76066 - (view) |
Author: Farshad Khoshkhui (farshad) |
Date: 2008-11-19 18:34 |
| I'm encountering random segfaults on multiple machines. By examining core dumps, it's all happening in stringobject.c (_PyString_Resize or string_join). By using pyframev I figured out it's always happening inside xmlrpclib.py (/usr/lib/python2.5/xmlrpclib.py (716): dump_struct or /usr/lib/python2.5/xmlrpclib.py (627): dumps) I'm using Python 2.5.2 on debian in a threaded environment with heavy use of xmlrpc. |
|
|
| msg76067 - (view) |
Author: Farshad Khoshkhui (farshad) |
Date: 2008-11-19 18:35 |
| Another Backtrace. I have three other core dumps with exact same backtrace on two different machines. |
|
|
| msg76069 - (view) |
Author: Thomas Heller (theller) *  |
Date: 2008-11-19 19:00 |
| Has nothing to do with ctypes (the package), unassigning. |
|
|
| msg76078 - (view) |
Author: Amaury Forgeot d'Arc (amaury.forgeotdarc) * |
Date: 2008-11-19 23:15 |
| This is difficult: the backtrace only show plain python operations. Some hints though: One backtrace shows a memory corruption in the obmalloc data. This may come from a buffer overrun. You initially selected ctypes in "Components", does this mean that your program also use ctypes? With ctypes it is easy to be caught with a python string converted to a (mutable) char* pointer. For example, on Windows: >>> import ctypes >>> c = ctypes.CDLL('msvcrt') >>> a = " " >>> c.strcpy(a, "X" * 50) 50 >>> a 'XXXX' ... and the crash is not far. Another case of corruption in obmalloc is to try to allocate python objects while the GIL is not held. This may happen if you wrote a C function that uses the Python API, and call this with ctypes. In any case, I suggest that you build and a use a debug-enabled version of python (configure with --with-pydebug). It catches some errors earlier and sometimes more reliably. |
|
|
| msg76091 - (view) |
Author: Farshad Khoshkhui (farshad) |
Date: 2008-11-20 07:00 |
| No, there isn't any custom made C extension, nor I'm using ctypes. (It was a mistake selecting ctypes). The application is a web service with postgresql backend, so it heavily uses pyexpat and pygresql in a threaded environment. I'll recompile python with pydebug and get back with results. |
|
|
| msg76184 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2008-11-21 14:23 |
| > The application is a web service with postgresql backend, so it > heavily uses pyexpat and pygresql in a threaded environment. pyexpat or pygresql is maybe not thread safe. To catch such error, you have to use Valgrind. And to use Valgrind, you have to recompile Python with the define "Py_USING_MEMORY_DEBUGGER": read Misc/valgrind.supp (comments at the top). Then, use "valgrind --suppressions=Misc/valgrind.supp <arguments...>". You might also try helgrind: "valgrind --tool=helgrind --suppressions=Misc/valgrind.supp <arguments...>". Note: remember me to translate this article to english! http://www.haypocalc.com/blog/index.php/2008/08/22/160-deboguer-programme-python-avec-gdb |
|
|
| msg83720 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2009-03-17 23:59 |
| farshad: Is the bug still open? If yes, can you give more informations? If you don't answer, I will have to close this issue because it's not possible find the bug with so few informations :-/ |
|
|
| msg84124 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2009-03-24 23:37 |
| There are not enough informations to reproduce the issue or understand the problem. Since farshad didn't answer since 4 months, I choose to close the bug. Reopen the bug if you have new informations! |
|
|