multithreading - Ways to end a worker process in a thread in Python 3 -
i wondering ways end worker thread in python 3.
if @ code sample this question worker has while true loop in , see q.task_done() called.
why worker automatically ended?
specifically interested in:
what options exist end workers infinite loop?
it seems options call break or return not sure if kill thread.
to clear want thread die when task has completed , not see ways kill thread documented anywhere.
#!python3 import threading queue import queue import time # lock serialize console output lock = threading.lock() def do_work(item): time.sleep(.1) # pretend lengthy work. # make sure whole print completes or threads can mix output in 1 line. lock: print(threading.current_thread().name,item) # worker thread pulls item queue , processes def worker(): while true: item = q.get() do_work(item) q.task_done() # create queue , thread pool. q = queue() in range(4): t = threading.thread(target=worker) t.daemon = true # thread dies when main thread (only non-daemon thread) exits. t.start() # stuff work items on queue (in case, number). start = time.perf_counter() item in range(20): q.put(item) q.join() # block until tasks done # "work" took .1 seconds per task. # 20 tasks serially 2 seconds. # 4 threads should .5 seconds (contrived because non-cpu intensive "work") print('time:',time.perf_counter() - start)
what options exist end workers infinite loop?
run while loop polling threading.semaphore object instance, rather constant true boolean. signal semaphore killing thread when want kill worker, , drop out of loop.
if want main thread wait worker finish, signal semaphore, , thread.join() block main thread until worker has finished doing whatever needs do. remember signal semaphore first, or hang ;)
that said, you've daemonized thread, don't need kill it. process die when there no non-daemon threads left alive. update remove daemon effect want thread exit cleanly, remove line:
t.daemon = true # thread dies when main thread (only non-daemon thread) exits. 