from queue import Queue
from threading import Thread
import time

_sentinel = object()

# A thread that produces data
def producer(out_q):
    n = 10
    while n > 0:
        # Produce some data
        out_q.put(n)
        time.sleep(2)
        n -= 1


    # Put the sentinel on the queue to indicate completion
    out_q.put(_sentinel)

# A thread that consumes data
def consumer(in_q):
    while True:
        # Get some data
        data = in_q.get()

        # Check for termination
        if data is _sentinel:
            in_q.put(_sentinel)
            break

        # Process the data
        print('Got:', data)
    print('Consumer shutting down')

if __name__ == '__main__':
    q = Queue()
    t1 = Thread(target=consumer, args=(q,))
    t2 = Thread(target=producer, args=(q,))
    t1.start()
    t2.start()
    t1.join()
    t2.join()