[rzimmerman]

Definitely - it is a total chore to get a threaded Python program to handle Ctrl-C/SIGINT properly.

Single-threaded Python handles it well - as long as you don't register a custom signal handler, Ctrl-C raises a KeyboardInterrupt exception immediately. KeyboardInterrupt is not a subclass of Exception, (it inherits from SystemExit, which inherits from BaseException directly), so any "except Exception:" clauses don't catch it. Which is the intent. This is also a primary reason to never use bare "except:" clauses (it will prevent Ctrl-C from working!).

For multithreaded Python, the easiest thing to do is just mark all your threads as daemon=True, so they die if the main thread exits. When you can't do that, the best bet is some "threading.Event" and custom SIGINT handler that triggers the event. I kind of wish SIGNINT by default would raise the KeyboardInterrupt in all threads, but I'm sure there are good reasons not to.