Mostly random pontification, delivered at irregular intervals.


Obtaining tracebacks on other threads than the current thread

Note: this entry was superseded and is maintained only for historical purposes. Among others, the restriction of not being able to find the stack frame for a specific thread has been lifted with changes in Python 2.3.

David Beazley added advanced debugging functions to the Python interpreter, and they have been folded into the 2.2 release.

I used these hooks to build a debugging module that is useful when you are looking for deadlocks in a multithreaded application. It basically has a single function that will return a list of the stack frames for all Python interpreter threads in the process.

Unfortunately, I was unable to find a way to get a stack frame for a specific thread (either by the thread ID or using threading Thread objects), as Python does not save the thread ID in its thread state.

Of course, I disclaim any liability if this code should crash your system, erase your homework, eat your dog (who also ate your homework) or otherwise have any undesirable effect.

Building and installing

Download threadframe-0.1.tar.gz. You can use the Makefile. I've built and tested this only on Solaris 8/x86 and Windows 2000, but the code should be pretty portable. There is a small test program that illustrates how to use this module to dump stack frames of all the Python interpreter threads. A sample run is available for your perusal.

For Windows users, a pre-compiled binary for the standard Python 2.2.1 distribution is available: threadframe.pyd. Just copy this file in any location in your Python path and you should be able to run the test script