I have been confronted to deadlocks in Zope, where the server
was there without taking any CPU but didn't answer any
request. It's pretty had to know where to look to find what's
happenning.



Maxime Yve found a very useful python module:
threadframe
. Using it, it's possible to dump tracebacks of
all running threads of a python process. I have a specialized
dumping product for a client that I'll make generic soon, to
debug any Zope.