Multiprocessing graceful stop

grace_stop.py

import time
import multiprocessing as mp
import queue as queuelib


N_PROCESSES = 4


def worker(queue: mp.Queue, stop: mp.Event):
    print(f"Start job: {mp.current_process().name}")

    while True:
        if stop.is_set():
            print('Will stop by signal')
            break

        try:
            value = queue.get(timeout=0.5)
        except (queuelib.Empty, mp.TimeoutError):
            continue
        result = value ** 2
        print(f'[{mp.current_process().name}] Result = {result}')
    print('End job')


if __name__ == '__main__':
    mp.set_start_method('spawn')
    stop = mp.Event()
    queue = mp.Queue()
    processes = [mp.Process(target=worker, args=(queue, stop))
                 for x in range(N_PROCESSES)]

    for p in processes:
        p.start()

    for n in range(1000):
        queue.put(n)

    time.sleep(1)
    stop.set()

    for p in processes:
        p.join()