import threading
import queue


def do_work(item):
    return item + 1


def worker():
    while True:
        item = q.get()
        if item is None:
            break
        result = do_work(item)
        q.task_done()


q = queue.Queue()

# Start Consumers
threads = []
num_worker_threads = 13     # Change this depending on your cores.
for i in range(num_worker_threads):
    thread = threading.Thread(target=worker)
    thread.start()
    threads.append(thread)

# Start Producer
for item in range(100):
    q.put(item)


# block until all tasks are done
q.join()


# stop workers
for i in range(num_worker_threads):
    q.put(None)
for t in threads:
    t.join()