python多进程程序之间交换数据的两种办法--Queue和Pipe

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import multiprocessing
import random
import time

class producer(multiprocessing.Process):
    def __init__(self, queue):
        multiprocessing.Process.__init__(self)
        self.queue = queue

    def run(self):
        for i in range(10):
            item = random.randint(0, 256)
            self.queue.put(item)
            print("Process Producer: item %d appended to queue %s " \
                  %(item, self.name))
            time.sleep(1)
            print("The size of queue is %s" \
                  % self.queue.qsize())


class consumer(multiprocessing.Process):
    def __init__(self, queue):
        multiprocessing.Process.__init__(self)
        self.queue = queue

    def run(self):
        while True:
            if (self.queue.empty()):
                print("the queue is empty")
                break
            else:
                time.sleep(2)
                item = self.queue.get()
                print("Process Consumer: item %d poped from by %s " \
                      % (item, self.name))
                time.sleep(1)

def create_items(pipe):
    output_pipe, _ = pipe
    for item in range(10):
        output_pipe.send(item)
    output_pipe.close()

def multiply_items(pipe_1, pipe_2):
    close, input_pipe = pipe_1
    close.close()
    output_pipe, _ = pipe_2
    try:
        while True:
            item = input_pipe.recv()
            output_pipe.send(item * item)
    except EOFError:
        output_pipe.close()
        

if __name__ == '__main__':

    queue = multiprocessing.Queue()
    process_producer = producer(queue)
    process_consumer = consumer(queue)
    process_producer.start()
    process_consumer.start()
    process_producer.join()
    process_consumer.join()
    
    pipe_1 = multiprocessing.Pipe(True)
    process_pipe_1 = multiprocessing.Process(target=create_items, args=(pipe_1,))
    process_pipe_1.start()
    pipe_2 = multiprocessing.Pipe(True)
    porcess_pipe_2 = multiprocessing.Process(target=multiply_items, args=(pipe_1, pipe_2,))
    porcess_pipe_2.start()

    pipe_1[0].close()
    pipe_2[0].close()

    try:
        while True:
            print (pipe_2[1].recv())
    except EOFError:
        print("End")