pythondaemonthread

① python daemon thread 什麼概念

daemon
A boolean value indicating whether this thread is a daemon thread (True) or not (False). This must be set before start() is called, otherwise RuntimeError is raised. Its initial value is inherited from the creating thread; the main thread is not a daemon thread and therefore all threads created in the main thread default to daemon = False.
The entire Python program exits when no alive non-daemon threads are left.
當daemon被設置為True時，如果主線程退出，那麼子線程也將跟著退出，
反之，子線程將繼續運行，直到正常退出。