Updates: The latest version is 0.30.9, released August 26, 2012.

OTrace is an object-oriented python debugger for nonlinear tracing of asynchronous or multithreaded interactive programs.Its features including taking “snapshots” of variables for tracing, “tagging” objects for tracking across different method invocations, and modifying live code (“monkey patching”) to insert print statements etc.

For more information, see the following documentation: