Concurrency and Modules

Queue Worker

A Queue hands work from one thread to another. The source stays in one pane, and replay uses thread colors to show producer and consumer events.

Producer and Consumer

queue_worker.py 
import queue
import threading


work = queue.Queue()


def producer(count):
    for number in range(1, count + 1):
        item = "job-" + str(number)
        work.put(item)
        print("queued=" + item)
    work.put("done")


def consumer():
    while True:
        item = work.get()
        if item == "done":
            print("stopped")
            break
        print("handled=" + item)


count = 

producer_thread = threading.Thread(target=producer, args=(count,))
consumer_thread = threading.Thread(target=consumer)

producer_thread.start()
consumer_thread.start()
producer_thread.join()
consumer_thread.join()

import queue
import threading


work = queue.Queue()


def producer(count):
    for number in range(1, count + 1):
        item = "job-" + str(number)
        work.put(item)
        print("queued=" + item)
    work.put("done")


def consumer():
    while True:
        item = work.get()
        if item == "done":
            print("stopped")
            break
        print("handled=" + item)


count = 

producer_thread = threading.Thread(target=producer, args=(count,))
consumer_thread = threading.Thread(target=consumer)

producer_thread.start()
consumer_thread.start()
producer_thread.join()
consumer_thread.join()
queue handoff `put()` adds work, and `get()` removes it. A small sentinel value can tell the consumer that no more work is coming.