Signals handled by Python (especially KeyboardInterrupt) may discard one level of exception handling. Consider the following code fragment: try: # outer exception handling level try: # inner exception handling level blocking_external_extension_function() except: print "inner exception handling" except: print "outer exception handling" Assume that "blocking_external_extension_function" is an external function (implemented in "C") that blocks until interrupted by a signal (EINTR) and then returns with an exception but without handling the signal. In our concrete case, "blocking_external_extension_function" has been "psycopg.connect" (the database "connect" from the Python-PostgreSQL bridge "psycopg"). In this case, when you interrupt the execution, while "blocking_external_extension_function" waits, the "KeyboardInterrupt" is not caught in the inner "try: ...except: ..." but only in the outer "try: ... except: ..." The following happens in detail in Python's main interpreter loop: * "blocking_external_extension_function" returns with an exception. * Python sets the next instruction to the exception handler of the inner exception handling * Python begins a new run through its main loop. At the start, it detects the "KeyboardInterrupt" signal. It now thinks, the "KeyboardInterrupt" were caused inside the inner exception handler and pops this exception handling level without executing it. The interpreter has lost one level of exception handling. The behaviour would probably better fit with expectations, when the interpreter would check for signals at the end of its main loop and before it sets its instruction pointer to the exception handler.
Logged In: YES user_id=752496 Please, could you verify if this problem persists in Python 2.3.4 or 2.4? If yes, in which version? Can you provide a test case? If the problem is solved, from which version? Note that if you fail to answer in one month, I'll close this bug as "Won't fix". Thank you! . Facundo
Logged In: YES user_id=6656 In addition, attaching any code samples rather than including them would seem a good idea. I can't make head or tail of the code in the summary.
Logged In: YES user_id=6656 Oh, after some judicious view-sourcing and query-replacing, I get the problem. However, I can't reproduce it (see attached script). So we're back to needing a failing example and more platform details.
