Is it possible to use GDB's reverse debugging with Python? How?

Question

I am trying to use GDB's reverse debugging with a Django application. I get it running in GDB, but I can't make it run backwards.

I stopped my Django app with Ctrl-Z and then entered reverse-next at the gdb prompt, getting the error message "Target multi-thread does not support this command."

Am I doing it wrong? Isn't this possible? Both?

Answer 1

That's an amazingly good question.

My first impulse would be to ensure I was using IPython as my shell for django and see if it's pdb support would help in this case. Pdb should have a very similar interface to gdb. As I recall, gdb is what's used to debug C/C++ programs, while django is being executed by a python interpreter. Using Pdb is here:

http://ericholscher.com/blog/2008/aug/31/using-pdb-python-debugger-django-debugging-series-/

Also you might want to try using django-extensions, for access to the werkzeug debugging view.

Answer 2

Before you can use GDB for reverse debugging, you must tell it to record your program execution (so it can play it back) via target record command, as documented here.

I am not sure this will help you debug your Django application though -- GDB is well suited for debugging "native" code (compiled C/C++), and is not well suited for debugging "interpreted" code (in either forward or reverse direction).