import multiprocessing
import os
import signal
import time


class Sleeper(multiprocessing.Process):
    def __init__(self, exit_event):
        self.exit_event = exit_event
        super(Sleeper, self).__init__()
        self.daemon = True

    def run(self):
        while not self.exit_event.is_set():
            time.sleep(1)


class Waiter(multiprocessing.Process):
    def __init__(self, exit_event):
        self.exit_event = exit_event
        super(Waiter, self).__init__()
        self.daemon = True

    def run(self):
        self.exit_event.wait()


if __name__ == '__main__':
    sleeper_exit_event = multiprocessing.Event()
    sleepers = []
    for i in range(2):
        sleepers.append(Sleeper(sleeper_exit_event))
        sleepers[i].start()
    time.sleep(1)
    os.kill(sleepers[0].pid, signal.SIGTERM)
    print("Setting sleeper exit event.")
    sleeper_exit_event.set()
    print("Event set - joining sleepers.")
    for s in sleepers:
        s.join()
    print("Sleepers joined.")

    waiter_exit_event = multiprocessing.Event()
    waiters = []
    for i in range(2):
        waiters.append(Waiter(waiter_exit_event))
        waiters[i].start()
    time.sleep(1)
    os.kill(waiters[0].pid, signal.SIGTERM)
    print("Setting waiter exit event.")
    waiter_exit_event.set() # blocks indefinitely
    print("Event set - joining waiters")
    for s in sleepers:
        s.join()
    print("Waiters joined.")