Segmentation faults using threads

[Mathias]

Dear ng,

I use the thread module (not threading) for a client/server app where I 
distribute large amounts of pickled data over ssh tunnels.
Now I get regular Segmentation Faults during high load episodes. I use a 
semaphore to have pickle/unpickle run nonthreaded, but I still get 
frequent nondeterministic segmentation faults.
Since there is no traceback after a sf, I have no clue what exactly 
happened, and debugging a multithreaded app is no fun anyway :(

Can someone recommend me how to get extra info during such a crash?
Or any other opinion on where the problem might lie?

Thanks a lot,
    Mathias