在python中的生产者和消费者线程上需要帮助 [英] Need help on producer and consumer thread in python

问题描述

我想同时在python中创建消费者和生产者线程，其中生产者线程将追加队列，消费者线程检索存储在队列中的项目.而且我需要与生产者一起启动消费者线程.使用者线程应等待队列获得项目.当队列中没有项目时，它应该终止.我是python的新手，请对此提供帮助.

I wanted to create the consumer and producer thread in python simultaneously, where producer thread will append the queue and consumer thread retrieves the item which stored in the queue. And I need to start the consumer thread along with producer. Consumer thread should wait till the queue gets an item. And it should terminate when there is no item in queue. I am new to python, please help on this.

要求:

如果有10个数字的列表，则生产者线程应将队列插入一个项目，而消费者线程应检索该数字.两个线程应同时启动.

If there is a list of 10 numbers, producer thread should insert the queue with one item, and consumer thread should retrieve the number. Both thread should start simultaneously .

from queue import Queue
import threading
import time

class producer(threading.Thread):

    def __init__(self, list_of_numbers):
        threading.Thread.__init__(self)
        self.list_items = list_of_numbers

    def run(self):
        for i in self.list_items:
            queue.put(str(i))

class consumer(threading.Thread):

    def __init__(self):
        threading.Thread.__init__(self)

    def run(self):
        while queue.not_empty:
            queue_ret = queue.get()
            print("Retrieved", queue_ret)


queue = Queue()
producers = producer([10,20,5,4,3,2,1])
consumers = consumer()

producers.start()
consumers.start()
producers.join()
consumers.join()

推荐答案

完成后只需放入一个特殊项目:

Just put a special item once you are done:

_im_done = object()

class producer(threading.Thread):
    def run(self):
        '''feed the consumer until you are done'''
        queue.put(_im_done)

class consumer(threading.Thread):
    def run(self):
        while True:
            queue_ret = queue.get()
            if queue_ret is _im_done:
                break
            '''normal execution'''

如果有多个消费者，则必须在停止之前将商品放回原处:

If there are multiple consumers, then you have to put the item back before you stop:

class consumer(threading.Thread):
    def run(self):
        while True:
            queue_ret = queue.get()
            if queue_ret is _im_done:
                queue.put(_im_done)
                break
            '''normal execution'''

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