[Python-Dev] Possible error in Python 2.4 garbage collector (original) (raw)

Kristján Valur Jónsson kristjan at ccpgames.com
Mon Nov 26 16:16:50 CET 2007

This is almost certainly not a bug in python. A cursory look indicates that a list being traversed in list_traverse has a NULL member. I'd suggest examining the other members of the list to figure out what this list is. Use the debugger for this, that is what it is for. It is probably a list you have created in your C code but forgot to check for exceptions when adding members to it, thus leaving one of them with a NULL pointer.

see for example http://wiki.python.org/moin/DebuggingWithGdb for tips on debugging.

K

-----Original Message----- From: python-dev-bounces+kristjan=ccpgames.com at python.org [mailto:python-dev-bounces+kristjan=ccpgames.com at python.org] On Behalf Of Moritz Mühlenhoff Sent: Monday, November 26, 2007 10:58 To: python-dev at python.org; muehlenhoff at univention.de Subject: [Python-Dev] Possible error in Python 2.4 garbage collector

Hi, we're running into a problem with the Python interpreter, which we suspect triggers a bug in the garbage collector or a related part of the memory management. We are using Python 2.4.4 in the version from Debian 4.0. Our C application imports various Python plugins using PyNodeCompile(). This used to work very well (it's a feature we've been using for years now), but if we import more than 23 modules we're running a segmentation fault with the backtrace below: (gdb) bt #0 0xb7ee9cad in visitdecref (op=0xb7287ec0, data=0x0) at ../Modules/gcmodule.c:269 #1 0xb7e716d1 in listtraverse (o=0xb724e62c, visit=0xb7ee9ca0 , arg=0x0) at ../Objects/listobject.c:2280 #2 0xb7eea729 in collect (generation=0) at ../Modules/gcmodule.c:294 #3 0xb7eeb0a3 in PyObjectGCMalloc (basicsize=20) at ../Modules/gcmodule.c:872

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