import time
import random
from multiprocessing import Process

def f():
    while True:
        time.sleep(10)

        dice = random.randint(1, 10)

        if dice == 1:
            raise ValueError
        elif dice == 2:
            break

if __name__ == "__main__":
    print(1)
    processes = [Process(target=f, daemon=False) for _ in range(20)]
    print(2)
    [p.start() for p in processes]
    print(3)
    [p.join() for p in processes]
    print(4)