Python多處理池隊列通信

Question

我正在嘗試實現一個並行運行並通過隊列進行通信的兩個進程池。

我們的目標是具有通過使用隊列傳遞消息到讀取器處理的寫入處理。

每個過程都在終端上打印反饋以獲得反饋。

這是代碼：

#!/usr/bin/env python

import os
import time
import multiprocessing as mp
import Queue

def writer(queue):
    pid = os.getpid()
    for i in range(1,4):
        msg = i
        print "### writer ", pid, " -> ", msg
        queue.put(msg)
        time.sleep(1)
        msg = 'Done'
    print '### '+msg
    queue.put(msg)

def reader(queue):
    pid = os.getpid()
    time.sleep(0.5)
    while True:
        print "--- reader ", pid, " -> ",
        msg = queue.get()
        print msg
        if msg == 'Done':
            break

if __name__ == "__main__":
    print "Initialize the experiment PID: ", os.getpid()
    mp.freeze_support()

    queue = mp.Queue()

    pool = mp.Pool()
    pool.apply_async(writer, (queue)) 
    pool.apply_async(reader, (queue))

    pool.close()
    pool.join()

我期待的輸出應該是這樣的：

Initialize the experiment PID: 2341
writer 2342 -> 1
reader 2343 -> 1
writer 2342 -> 2
reader 2343 -> 2
writer 2342 -> 3
reader 2343 -> 3
Done

但是我只得到了這條線：

Initialize the experiment PID: 2341

然后腳本退出。

在通過隊列進行通信的池中實現兩個進程的進程間通信的正確方法是什么？

Answer 1

我使用mp.Manager().Queue()作為隊列，因為我們無法直接傳遞Queue 。 嘗試直接使用Queue導致異常但由於我們使用apply_async 。

我將您的代碼更新為：

#!/usr/bin/env python

import os
import time
import multiprocessing as mp
import Queue

def writer(queue):
    pid = os.getpid()
    for i in range(1,4):
        msg = i
        print "### writer ", pid, " -> ", msg
        queue.put(msg)
        time.sleep(1)
        msg = 'Done'
    print '### '+msg
    queue.put(msg)

def reader(queue):
    pid = os.getpid()
    time.sleep(0.5)
    while True:
        print "--- reader ", pid, " -> ",
        msg = queue.get()
        print msg
        if msg == 'Done':
            break

if __name__ == "__main__":
    print "Initialize the experiment PID: ", os.getpid()
    manager = mp.Manager()

    queue = manager.Queue()

    pool = mp.Pool()
    pool.apply_async(writer, (queue,))
    pool.apply_async(reader, (queue,))

    pool.close()
    pool.join()

我得到了這個輸出：

Initialize the experiment PID:  46182
### writer  46210  ->  1
--- reader  46211  ->  1
### writer  46210  ->  2
--- reader  46211  ->  2
### writer  46210  ->  3
--- reader  46211  ->  3
### Done
--- reader  46211  ->  Done

我相信這是你的期望。