Python 多处理池队列通信

Question

我正在尝试实现一个包含两个进程的池，这两个进程运行并行并通过队列进行通信。

目标是让一个 writer 进程通过使用队列.

每个进程都在终端上打印反馈，以便得到反馈。

代码如下：

#!/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()

我期望的输出应该是这样的：

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

但是我只得到一行：

Initialize the experiment PID: 2341

然后脚本退出。

通过队列通信的池中两个进程的进程间通信的正确实现方式是什么？

Answer 1

我用mp.Manager().Queue()作为队列，因为不能直接传Queue。尝试直接使用 Queue 导致异常，但由于我们使用 apply_async 而未得到处理。

我将您的代码更新为：

#!/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()

我得到了这个输出：

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

相信这就是您所期望的。

Python 多处理池队列通信

Python multiprocessing Pool Queues communication

python

multiprocessing

python-2.7