Question

我要做什么：

在创建多处理池后发生异常时，当父进程终止时，子进程将变成僵尸。为了解决这个问题，我捕获了异常，并明确并收获了池中的所有子代。

问题是

这会导致父级挂起，而不是退出并返回到终端命令行。

后一种行为是意外的，我不知道为什么。但是回溯表明这是池中的问题。

问题是 为什么会挂起？

import multiprocessing as mp

def deadPool():
    print("Everybody out of the pool")
    active = mp.active_children()
    for a in active:
        print("reaping",a)
        a.terminate()
    print('deadpool')

try:
    pool = mp.Pool(mp.cpu_count()//2)
    print (" running with pool of ",mp.cpu_count()//2)
    p = 1/0  # intentional bug to generate exception

finally:
    deadPool()

这里是对此的调用：

python ~/Documents/testMp.py 
 running with pool of  4
Everybody out of the pool
reaping <ForkProcess(ForkPoolWorker-1, started daemon)>
reaping <ForkProcess(ForkPoolWorker-4, started daemon)>
reaping <ForkProcess(ForkPoolWorker-2, started daemon)>
reaping <ForkProcess(ForkPoolWorker-3, started daemon)>
deadpool
Traceback (most recent call last):
  File "/Users/foo/testMp.py", line 15, in <module>
    p = 1/0  # intentional bug 
ZeroDivisionError: division by zero

这时父进程已挂起。

按Ctrl-c退出此挂起的进程可发出键盘异常，并返回到终端提示

^CError in atexit._run_exitfuncs:
Traceback (most recent call last):
  File "/Users/foo/anaconda3/envs/jupyter2/lib/python3.7/multiprocessing/util.py", line 265, in _run_finalizers
    finalizer()
  File "/Users/foo/anaconda3/envs/jupyter2/lib/python3.7/multiprocessing/util.py", line 189, in __call__
    res = self._callback(*self._args, **self._kwargs)
  File "/Users/foo/anaconda3/envs/jupyter2/lib/python3.7/multiprocessing/pool.py", line 581, in _terminate_pool
    cls._help_stuff_finish(inqueue, task_handler, len(pool))
  File "/Users/foo/anaconda3/envs/jupyter2/lib/python3.7/multiprocessing/pool.py", line 566, in _help_stuff_finish
    inqueue._rlock.acquire()
KeyboardInterrupt

如您所见，它似乎卡在了“ _terminate_pool”中，这与多进程有关

如何收割孩子并退出python多处理池

0 个答案: