Share state between python coprocesses

multi-queue.py

import time
import random

from multiprocessing import Process, Queue, current_process, freeze_support

#
# Function run by worker processes
#

def worker(state, input, output):
    key_len = len(state)
    for arg in iter(input.get, 'STOP'):
        result = "Process: {} lookup: {} -> {}".format(current_process().name,
                arg, state[arg % key_len])
        time.sleep(2)
        output.put(result)


def test():
    NUMBER_OF_PROCESSES = 4
    TASKS1 = [i for i in range(20)]
    TASKS2 = [i + 1 for i in range(10)]

    # Create queues
    task_queue = Queue()
    done_queue = Queue()

    # Submit tasks
    for task in TASKS1:
        task_queue.put(task)

    state = {0: 0, 1: 10, 2: 20, 3: 30, 4: 40}
    # Start worker processes
    for i in range(NUMBER_OF_PROCESSES):
        Process(target=worker, args=(state, task_queue, done_queue)).start()

    # Get and print results
    print('Unordered results:')
    for i in range(len(TASKS1)):
        print('\t', done_queue.get())

    # Add more tasks using `put()`
    for task in TASKS2:
        task_queue.put(task)

    # Get and print some more results
    for i in range(len(TASKS2)):
        print('\t', done_queue.get())

    # Tell child processes to stop
    for i in range(NUMBER_OF_PROCESSES):
        task_queue.put('STOP')


if __name__ == '__main__':
    freeze_support()
    test()