There have been a couple of reports from various people (myself included) about a bug that will cause Zope to mysteriously die and dump core. I myself had the same problem, particularly with MySQLdb on recent versions of Python. I decided I better hunt the bastard down sooner rather than later... Symptoms: Mysterious core dumps fairly early on after starting up MySQLdb, isolated to the first query. After some investigation, I determined that this did not occur with Python 1.5.2 or 2.0, but does occur with 2.0.1, 2.1, and 2.1.1. Now, when calling _mysql.connect(), one of the items that you MySQLdb will pass in is a type conversion dictionary as a keyword argument, i.e. apply(connect, args, kwargs). After injecting some print statements here and there, and some getrefcount(), I found that the refcount on the converter dictionary was going to zero, i.e. getrefcount() returns 1. However, this only happened with Python > 2.0. So I got out diff and found the critical difference between 2.0 (MySQLdb not broken) and 2.0.1 (MySQLdb broken): diff -u -r Python-2.0/Python/getargs.c Python-2.0.1/Python/getargs.c --- Python-2.0/Python/getargs.c Mon Oct 16 17:49:29 2000 +++ Python-2.0.1/Python/getargs.c Sat Mar 31 08:18:35 2001 @@ -1124,6 +1124,7 @@ return 0; } converted++; + Py_DECREF(item); } else { PyErr_Clear(); The general upshot of this is: In versions of Python (numerically) prior to 2.0.1, if you use the O format with PyArgs_ParseTupleAndKeywords() (and possibly also PyArgs_ParseTuple()) to return a PyObject *, you get a new reference. In 2.0.1 and later, you get a borrowed reference and must Py_INCREF() if you want to keep it. In Python 1.5.2, however, doing this causes a memory leak! Since I want to keep compatibility with Python 1.5.2 for now, my solution is this: if (!conv) conv = PyDict_New(); #if PY_VERSION_HEX > 0x02000100 else Py_INCREF(conv); #endif In this example, conv is initialized to NULL, and PyArgs_ParseTupleAndKeywords() may or may not set it to some object pointer if it was passed in. Since Zope is only going to be supporting 2.1 and newer releases, this is not necessary. However, it may be worth auditing the code to see if the O format is being used, and if so, do Py_INCREF()s need to be added. I suspect some might, since with Python 1.5.2, having them there is a memory leak. I'm going to bed now... -- Andy Dustman PGP: 0x930B8AB6 @ .net http://dustman.net/andy I'll give spammers one bite of the apple, but they'll have to guess which bite has the razor blade in it.