This product adds a hook so that a deadlocked Zope process can be debugged, by dumping a traceback of all running python processes. The dump is sent to the event log (at the DEBUG level) and returned to the browser (even though the Zope is deadlocked and doesn't answer any other requests!).
DeadlockDebugger can of course also be used to debug Zope in non-deadlock situations, when a Zope process is taking a long time and you wish to know what code is being executed.