[英]Python multiprocessing Pool Queues communication
我正在尝试实现一个并行运行并通过队列进行通信的两个进程池。
我们的目标是具有通过使用队列传递消息到读取器处理的写入处理。
每个过程都在终端上打印反馈以获得反馈。
这是代码:
#!/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
但是我只得到了这条线:
Initialize the experiment PID: 2341
然后脚本退出。
在通过队列进行通信的池中实现两个进程的进程间通信的正确方法是什么?
我使用mp.Manager().Queue()
作为队列,因为我们无法直接传递Queue
。 尝试直接使用Queue
导致异常但由于我们使用apply_async
。
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
我相信这是你的期望。
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