import multiprocessing as mp
from time import sleep

def read_thread_func(queue, num_writers):
    threads_closed = 0

    while threads_closed < num_writers:
        message = queue.get(block=True, timeout=60)

        if message == "[THREAD_CLOSING]":
            threads_closed += 1
        else:
            print(message)

def write_thread_func(queue, pid):
    try:
        for i in range(5):
            sleep(1)
            queue.put("iterating pid = {}, i = {}\n".format(pid, i))
    finally:
        queue.put("[THREAD_CLOSING]")


if __name__ == '__main__':
    manager = mp.Manager()

    pool = mp.Pool(mp.cpu_count())

    results = []

    # num write threads per read thread
    num_write_threads = 4

    # here we make multiple write thread/read thread groups
    # in quick succession
    for queue in range(3):
        queue = manager.Queue()

        # if we uncomment this line we avoid the crash
        #sleep(0.5)

        results.append(pool.apply_async(read_thread_func, args=[queue, num_write_threads]))

        for i in range(num_write_threads):
            results.append(pool.apply_async(write_thread_func, args=[queue, i]))

    pool.close()
    pool.join()

    # print possible exceptions
    for result in results:
        print(result.get())