queue模块

Python提供了Queue模块来专门实现消息队列

Queue对象

    Queue对象实现一个fifo队列（其他的还有lifo、priority队列，这里不再介绍）。queue只有maxsize一个构造参数，用来指定队列容量，指定为0的时候代表容量无限。主要有以下成员函数：

    Queue.qsize()：返回消息队列的当前空间。返回的值不一定可靠。

    Queue.empty()：判断消息队列是否为空，返回True或False。同样不可靠。

    Queue.full()：类似上边，判断消息队列是否满

    Queue.put(item, block=True, timeout=None)：往消息队列中存放消息。block可以控制是否阻塞，timeout指定阻塞时候的等待时间。如果不阻塞或者超时，会引起一个full exception。

    Queue.put_nowait(item)：相当于put(item, False).

    Queue.get(block=True, timeout=None)：获取一个消息，其他同put。

以下两个函数用来判断消息对应的任务是否完成。

    Queue.task_done()：接受消息的线程通过调用这个函数来说明消息对应的任务已完成。

    Queue.join()： 实际上意味着等到队列为空，再执行别的操作

程序示例代码如下：
 

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author :Alvin.xie
# @Time :2017-12-18 16:48
# @file :4.py

import random, threading, time
from Queue import Queue


# Producer thread
class Producer(threading.Thread):
    def __init__(self, t_name, queue):
        threading.Thread.__init__(self, name=t_name)
        self.data = queue

    def run(self):
        for i in range(10): # 随机产生10个数字 ，可以修改为任意大小
            # randomnum=random.randint(1,99)
            print "%s: %s is producing %d to the queue!" % (time.ctime(), self.getName(), i)
            self.data.put(i) # 将数据依次存入队列
            # time.sleep(1)
        print "%s: %s finished!" % (time.ctime(), self.getName())


# Consumer thread
class Consumer_even(threading.Thread):
    def __init__(self, t_name, queue):
        threading.Thread.__init__(self, name=t_name)
        self.data = queue

    def run(self):
        while 1:
            try:
                val_even = self.data.get(1, 5) # get(self, block=True, timeout=None) ,1就是阻塞等待,5是超时5秒
                if val_even % 2 == 0:
                    print "%s: %s is consuming. %d in the queue is consumed!" % (time.ctime(), self.getName(), val_even)
                    time.sleep(2)
                else:
                    self.data.put(val_even)
                    time.sleep(2)
            except: # 等待输入，超过5秒  就报异常
                print "%s: %s finished!" % (time.ctime(), self.getName())
                break


class Consumer_odd(threading.Thread):
    def __init__(self, t_name, queue):
        threading.Thread.__init__(self, name=t_name)
        self.data = queue

    def run(self):
        while 1:
            try:
                val_odd = self.data.get(1, 5)
                if val_odd % 2 != 0:
                    print "%s: %s is consuming. %d in the queue is consumed!" % (time.ctime(), self.getName(), val_odd)
                    time.sleep(2)
                else:
                    self.data.put(val_odd)
                    time.sleep(2)
            except:
                print "%s: %s finished!" % (time.ctime(), self.getName())
                break


# Main thread
def main():
    queue = Queue()
    producer = Producer('Pro.', queue)
    consumer_even = Consumer_even('Con_even.', queue)
    consumer_odd = Consumer_odd('Con_odd.', queue)
    producer.start()
    consumer_even.start()
    consumer_odd.start()
    producer.join()
    consumer_even.join()
    consumer_odd.join()
    print 'All threads terminate!'


if __name__ == '__main__':
    main()

执行结果如下：
Mon Dec 18 16:49:04 2017: Pro. is producing 0 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 1 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 2 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 3 to the queue!
Mon Dec 18 16:49:04 2017: Con_even. is consuming. 0 in the queue is consumed!
Mon Dec 18 16:49:04 2017: Pro. is producing 4 to the queue!
Mon Dec 18 16:49:04 2017: Con_odd. is consuming. 1 in the queue is consumed!
Mon Dec 18 16:49:04 2017: Pro. is producing 5 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 6 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 7 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 8 to the queue!
Mon Dec 18 16:49:04 2017: Pro. is producing 9 to the queue!
Mon Dec 18 16:49:04 2017: Pro. finished!
Mon Dec 18 16:49:06 2017: Con_even. is consuming. 2 in the queue is consumed!
Mon Dec 18 16:49:06 2017: Con_odd. is consuming. 3 in the queue is consumed!
Mon Dec 18 16:49:08 2017: Con_even. is consuming. 4 in the queue is consumed!
Mon Dec 18 16:49:08 2017: Con_odd. is consuming. 5 in the queue is consumed!
Mon Dec 18 16:49:10 2017: Con_even. is consuming. 6 in the queue is consumed!
Mon Dec 18 16:49:10 2017: Con_odd. is consuming. 7 in the queue is consumed!
Mon Dec 18 16:49:12 2017: Con_even. is consuming. 8 in the queue is consumed!
Mon Dec 18 16:49:12 2017: Con_odd. is consuming. 9 in the queue is consumed!
Mon Dec 18 16:49:19 2017: Con_even. finished!
Mon Dec 18 16:49:19 2017: Con_odd. finished!
All threads terminate!


Process finished with exit code 0