Track down every piece of code that could hang because of a KeyboardInterrupt

[Yomguithereal]

And edit the startup hook to make threads die before waiting barrier, or break the barrier

[Yomguithereal]

We still have an error possible when booting the dispatcher and when join the threads in exit

[Yomguithereal]

Maybe state also needs to release condition on imap cleanup.

[Yomguithereal]

raise KeyboardInterrupt in cleanup and shutdown

[Yomguithereal]

Basically the issue is this one: https://stackoverflow.com/questions/18637048/avoid-exception-ignored-in-python-enhanced-generator when a KeyboardInterrupt is fire in the cleanup phase (finally in the output generator or the __exit__ teardown).

[Yomguithereal]

Also see PEP419: https://www.python.org/dev/peps/pep-0419/

[Yomguithereal]

Also see this ref: https://vorpus.org/blog/control-c-handling-in-python-and-trio/