> I will try with pdb or something.

You can also try to attach gdb to the running process: with
python-gdb.py, you have nice py-* commands.

Or if you don't have gdb7, you may try my faulthandler module: you will
have to modify the source code (eg. Lib/test/regrtest.py) to add at the
top:

   import faulthandler, signal; faulthandler.register(signal.SIGUSR1)

Then you can display the current Python backtrace by sending a SIGUSR1
signal to the running Python process (eg. killall -USR1 python).

https://github.com/haypo/faulthandler/wiki