queue 队列

queue用来在进程间传递消息，任何可以pickle-able的对象都可以在加入到queue。 multiprocessing.JoinableQueue 是 Queue的子类，增加了task_done()和join()方法。 task_done()用来告诉queue一个task完成。一般地在调用get()获得一个task，在task结束后调用task_done()来通知Queue当前task完成。 join() 阻塞直到queue中的所有的task都被处理（即task_done方法被调用）

import time
import multiprocessing

class Consumer(multiprocessing.Process):
    def __init__(self,task_queue,result_queue):
        multiprocessing.Process.__init__(self)
        self.task_queue = task_queue
        self.result_queue = result_queue
        
    def run(self):
        process_name = self.name
        while True:
            next_queue = self.task_queue.get()
            if next_queue is None:
                self.task_queue.task_done()
                print("%s,exiting"%(process_name))
                break
            print("%s:%s"%(process_name,next_queue))
            self.result_queue.put(next_queue())
            self.task_queue.task_done()
            return 
    
class Task(object):
    def __init__(self,a,b):
        self.a = a
        self.b = b
    
    def __call__(self):
#         return "%s * %s = %s"%(self.a,self.b,self.a*self.b)
        pass
    
    def __str__(self):
        return "%s * %s"%(self.a,self.b)
    
if __name__ == '__main__':
    # 1.创建队列
    tasks = multiprocessing.JoinableQueue()
    results = multiprocessing.SimpleQueue()
    
    # 2.开启消费者
    consumers = [Consumer(tasks,results) for i in range(20)]
    for t in consumers:
        t.start()
        
    # 3.任务队列
    number_jobs = 10
    for i in range(number_jobs):
        tasks.put(Task(i,i))
        
    # 4. 添加终止None
    for i in range(number_jobs):
        tasks.put(None)
    
    tasks.join()
    
    # 5. 输出返回值
    while number_jobs:
        result = results.get()
        print("result:",result)
        number_jobs -= 1

Consumer-42:1 * 1
Consumer-43:2 * 2
Consumer-44:3 * 3
Consumer-45:4 * 4
Consumer-41:0 * 0
Consumer-46:5 * 5
Consumer-47:6 * 6
Consumer-48:7 * 7
Consumer-49:8 * 8
Consumer-50:9 * 9
Consumer-53,exiting
Consumer-52,exiting
Consumer-54,exiting
Consumer-51,exiting
Consumer-60,exiting
result: 1 * 1 = 1
result: 2 * 2 = 4
result: 3 * 3 = 9
result: 4 * 4 = 16
result: 5 * 5 = 25
result: 0 * 0 = 0
result: 6 * 6 = 36
result: 7 * 7 = 49
result: 8 * 8 = 64
result: 9 * 9 = 81
Consumer-58,exiting
Consumer-55,exiting
Consumer-56,exiting
Consumer-57,exiting
Consumer-59,exiting