interrupt or sigterm multiprocessing pool gracefully

gracefully_quit_multiprocessing_pool.py

import os
import sys
import time
import signal
from multiprocessing import Pool

def int_handler(signum, frame):
    print('(%s) int_handler' % os.getpid())
    raise KeyboardInterrupt()

def worker(x):
    try:
        while True:
            time.sleep(1)
            print('(%s) loop' % os.getpid())
    except KeyboardInterrupt:
        print('(%s) worker exception' % os.getpid())
    sys.exit(0)

def main(args):
    print('(%s) main' % os.getpid())

    signal.signal(signal.SIGTERM, int_handler)
    signal.signal(signal.SIGINT, int_handler)
    
    pool = Pool(processes=4)
    try:
        results = pool.map_async(worker, range(4)) # 必须用异步接口，否者主进程被阻塞，不会执行int_handler
        while not results.ready():
            results.wait(0.1)
        lst = results.get()
    except KeyboardInterrupt:
        print('(%s) main exception' % os.getpid())
        pool.close()
        pool.terminate()
        print('(%s) terminate' % os.getpid())
    except Exception as e:
        pool.close()
        pool.terminate()
        print('pool is terminated')

if __name__ == '__main__':
    main(sys.argv)