producer consumer problem

producer-consumer-problem.py

from multiprocessing import Queue as mQueue, Process
from multiprocessing.sharedctypes import Value
import ctypes
import time
import random

def consumer(i, q):
    while True:
       item = q.get()
       if item is None:
           print '[C%d]: end' % i
           q.put(None)
           break
       time.sleep(3)
       print '[C%d]: consume %d' % (i, item)


def producer(i, q, isend):
    n = 1
    while True:
        print '[P%d]: produce %d' % (i, n)
        q.put(n)
        if isend.value == 1:
            break
        time.sleep(2)
        n += 1
    print '[P%d]: end' % i


isend = Value(ctypes.c_int, 0)
q = mQueue()
cs = [Process(target=consumer, args=(i, q)) for i in range(3)]
ps = [Process(target=producer, args=(i, q, isend)) for i in range(3)]
for c in cs:
    c.start()
for p in ps:
    p.start()

raw_input()

# finalize
isend.value = 1
for p in ps:
    p.join()
for i in range(10):
    q.put(None)
for c in cs:
    c.join()