[Zope] Zope eating CPU/RAM - how do I find the culprit?

[Cees de Groot]

Our production Zope machine has developed a habit over Christmas where
it starts eating CPU and RAM (one Python thread on 100% CPU time, and 
I've seen kernel messages indicating that Zope was killed because it
hit an out-of-memory condition which means it sat on ~500Mb RAM). 

I'm completely in the dark about what causes this (probably some of
my own code, I installed some new bits a couple of days ago), but what's
worse: I really don't know how to set about finding the problematic
code. Is there a way to find out what code a thread is running?

-- 
Cees de Groot               http://www.cdegroot.com     <cg@cdegroot.com>
GnuPG 1024D/E0989E8B 0016 F679 F38D 5946 4ECD  1986 F303 937F E098 9E8B