python multiprocessing example

from multiprocessing import Process, Queue
from Queue import Empty

MAX_MSG = 200000
NUM_PROC = 10

def startProducer(queue, out, max):
	import time, random
	time.sleep(2)
	for i in range(max):
		queue.put("hello %s"%i)
		#time.sleep(0.01)
	queue.put("quit")
	out.put("producer_done")

def startConsumer(queue, out, name):
	counter = 0
	while True:
		value = queue.get()
		if value == "quit":
			# put it back in the queue to kill others
			queue.put("quit")
			break
		counter += 1
		out.put("%s got value %s"%(name, value))
	out.put("%s processed %s messages"%(name, counter))

if __name__=='__main__':
	q = Queue()
	out = Queue()
	p = Process(target=startProducer, args=(q, out, MAX_MSG))
	p.start()

	for i in range(NUM_PROC):
		p = Process(target=startConsumer, args=(q, out, "consumer%s"%i))
		p.start()
	print("all started")

	try:
		# long timeout for first read (for producer start delay)
		val = out.get(True, 20)
		while True:
			print("val: %s"%val)
			val = out.get(True, 2)
	except Empty:
		print("queue timeout")
	except:
		print("unknown error")