python生产者/消费者示例

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标准线程多进程，生产者/消费者示例。一个生产者，一个消费者，实现如下：

# coding: utf-8import threadingimport timeimport Queueclass Consumer(threading.Thread):    def __init__(self, queue):        threading.Thread.__init__(self)        self._queue = queue    def run(self):        while True:            msg = self._queue.get()            if isinstance(msg, str) and msg == 'quit':                break            time.sleep(1)            print 'consumer receive msg: %s' % msg        print 'consumer finished'def Producer():    q = Queue.Queue()    c = Consumer(q)    c.start()    i = 0    while i < 10:        print 'producer put msg: %s' % i        q.put(str(i))        time.sleep(0.5)        i += 1    q.put('quit')    c.join()if __name__ == '__main__':    Producer()

为了提高处理速度，我们会许要多个消费者。这是可以把消费者放到一个线程池中进行管理。一个生产者，多个消费者时，实现如下：

# coding: utf-8import threadingimport timeimport Queueclass Consumer(threading.Thread):    def __init__(self, queue):        threading.Thread.__init__(self)        self._queue = queue    def run(self):        while True:            msg = self._queue.get()            if isinstance(msg, str) and msg == 'quit':                break            time.sleep(1)            print 'consumer receive msg: %s' % msg        print 'consumer finished'def build_consumer_pool(size, queue):    consumers = []    for i in range(size):        c = Consumer(queue=queue)        c.start()        consumers.append(c)    return consumersdef Producer():    q = Queue.Queue()    consumers = build_consumer_pool(3, q)    i = 0    while i < 12:        print 'producer put msg: %s' % i        q.put(str(i))        i += 1    for c in consumers:        q.put('quit')    for c in consumers:        c.join()if __name__ == '__main__':    Producer()

上面的代码都是些基础功能，而且很容易出错。Python提供了更加优雅的线程池实现，multiprocessing模块中的Pool非常好用。

# coding: utf-8from multiprocessing.dummy import Pool as ThreadPoolimport timedef consumer(msg):    print 'consumer receive msg: %s' % msg    time.sleep(1)    return msgdef producer():    items = []    pool = ThreadPool(4)    i = 0    while i < 12:        print 'producer put msg: %s' % i        items.append(str(i))        i += 1    results = pool.map(consumer, items)    pool.close()    pool.join()    print resultsif __name__ == '__main__':    producer()

这里map方法极大简化了对多线程的处理，代码也更优美、可靠。

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