一个线程写入队列，一个线程读取

Question

我试图让一个线程将项目添加到队列中，并让主线程将它们拉出。我正在尝试的方法在阅读多处理文档后不起作用。我究竟做错了什么？谢谢。

import time
from multiprocessing import Process, Queue

def append_to_queue(q, t=1):
    n = 0
    while True:
        q.put(n)
        n += 1
        time.sleep(t)

def print_queue(q, t=0.5):
    while True:
        print q.get()
        time.sleep(t)

def main(t1, t2, delay=1):
    q = Queue()
    p = Process(target=append_to_queue, args=(q, t1,))
    p.start()
    time.sleep(delay)
    print_queue(q, t2)
    p.join()

main(1, 0.5, delay=1)

Answer 1

1. 您使用的是进程而不是线程
2. 您实际上使用了一个生产流程，但您在主流程中只消耗一次。我想你想要一个消费过程。

这是一个演示：

import time
from multiprocessing import Process, Queue, Event

def append_to_queue(t, q, stopnow):
    n = 0
    while not stopnow.is_set():
        q.put(n)
        n += 1
        time.sleep(t)
    q.put("producer done") # consumer will print this

def print_from_queue(t, q, stopnow):
    while not stopnow.is_set():
        print q.get()
        time.sleep(t)
    # drain queue
    for msg in xrange(q.qsize()):
        print msg
    print "consumer done"

def main(t1, t2):
    # @eryksun:
    # Because windows doesn't fork - the Queue
    # and Event can't be inherited from the main process.
    # Create them in main and pass them in the args tuple.
    q = Queue()
    stopnow = Event()
    producer = Process(target=append_to_queue, args=(t1, q, stopnow))
    producer.start()
    consumer = Process(target=print_from_queue, args=(t2, q, stopnow,))
    consumer.start()
    time.sleep(5)
    stopnow.set()
    producer.join()
    consumer.join()

# @eryksun:
# Windows doesn't fork, so you need to use if __name__ == '__main__'
# to guard calling main
if "__main__" == __name__:
    main(1, 0.5)