Multithreading - Active threads & enumerate()
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Python Multithread
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threading.enumerate()
It is not necessary to retain an explicit handle to all of the daemon threads in order to ensure they have completed before exiting the main process.
threading.enumerate() returns a list of all Thread objects currently alive. The list includes daemonic threads, dummy thread objects created by current_thread(), and the main thread. It excludes terminated threads and threads that have not yet been started.
import threading import time import logging import random logging.basicConfig(level=logging.DEBUG, format='(%(threadName)-9s) %(message)s',) def f(): t = threading.currentThread() r = random.randint(1,10) logging.debug('sleeping %s', r) time.sleep(r) logging.debug('ending') return if __name__ == '__main__': for i in range(3): t = threading.Thread(target=f) t.setDaemon(True) t.start() main_thread = threading.current_thread() for t in threading.enumerate(): if t is main_thread: continue logging.debug('joining %s', t.getName()) t.join()
After threading.enumerate() gathers all active threads including the calling thread (main_thread), the code calls join() methods of those threads except the main_thread.
Output:
(daemon ) Starting (non-daemon) Starting (non-daemon) Exiting
Output looks like this:
(Thread-1 ) sleeping 6 (Thread-2 ) sleeping 10 (MainThread) joining Thread-1 (Thread-3 ) sleeping 5 (Thread-3 ) ending (Thread-1 ) ending (MainThread) joining Thread-2 (Thread-2 ) ending (MainThread) joining Thread-3
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