attaching debugger to runinng python program

[Nebur]

You may try winpdb.
I find it to be a comfortable debugger that also can attach to running
programs. (You need to add a line in your code where the program should
stop and wait for the debugger to attach.)
I am satisfied with it, but I did not debug a multi theaded app.
However, it can handle threads. I'd be glad to later hear whether it
did what you need, or not:

http://www.digitalpeers.com/pythondebugger/threads.htm

Regards, Ruben