from multiprocessing import Pool, TimeoutError
import time
import os

def print_for_three_seconds():
    for i in range(12):
        print(i)
        time.sleep(0.25)

def crash_in_one_second():
    time.sleep(1)
    raise Exception(f"Intentionally crashing from thread {os.getpid()}")

def die_completely(e):
    print(f"die_completely callback executed in thread {os.getpid()}")
    pool.terminate()
    raise Exception("Child process threw an exception", e)

if __name__ == '__main__':
    pool = Pool(processes=4)              # start 4 worker processes

    for _ in range(3):
        pool.apply_async(print_for_three_seconds, error_callback=die_completely)
    pool.apply_async(crash_in_one_second, error_callback=die_completely)
    pool.close()
    print(f"Main thread pid={os.getpid()} ready to join")
    pool.join()

    print("Done.")