Question

我正在尝试多处理系统命令，但无法使用简单的程序。函数runit（cmd）工作正常但是......

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输出：

#!/usr/bin/python3
from subprocess import call, run, PIPE,Popen
from multiprocessing import Pool
import os
pool = Pool()

def runit(cmd):
    proc = Popen(cmd, shell=True,stdout=PIPE, stderr=PIPE, universal_newlines=True)
    return proc.stdout.read()

#print(runit('ls -l'))

it = []
for i in range(1,3):
    it.append('ls -l')

results = pool.map(runit, it)

然后它以某种方式等待并且什么都不做，当我按下Ctrl + C几次时它会吐出来：

Process ForkPoolWorker-1:
Process ForkPoolWorker-2:
Traceback (most recent call last):
Traceback (most recent call last):
  File "/usr/lib/python3.5/multiprocessing/process.py", line 249, in _bootstrap
    self.run()
  File "/usr/lib/python3.5/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python3.5/multiprocessing/pool.py", line 108, in worker
    task = get()
  File "/usr/lib/python3.5/multiprocessing/queues.py", line 345, in get
    return ForkingPickler.loads(res)
AttributeError: Can't get attribute 'runit' on <module '__main__' from './syscall.py'>
  File "/usr/lib/python3.5/multiprocessing/process.py", line 249, in _bootstrap
    self.run()
  File "/usr/lib/python3.5/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib/python3.5/multiprocessing/pool.py", line 108, in worker
    task = get()
  File "/usr/lib/python3.5/multiprocessing/queues.py", line 345, in get
    return ForkingPickler.loads(res)
AttributeError: Can't get attribute 'runit' on <module '__main__' from './syscall.py'>

Answer 1

我不确定，因为我所知道的问题与Windows相关（而且我无法访问Linux机箱进行重新呈现），但为了便于携带，您必须包装多处理器 - if __name__=="__main__"中的依赖命令或它与python生成进程的方式冲突：固定示例在Windows上运行正常（并且在其他平台上也可以正常工作）：

from multiprocessing import Pool
import os

def runit(cmd):
    proc = Popen(cmd, shell=True,stdout=PIPE, stderr=PIPE, universal_newlines=True)
    return proc.stdout.read()

#print(runit('ls -l'))

it = []
for i in range(1,3):
    it.append('ls -l')

if __name__=="__main__":
    # all calls to multiprocessing module are "protected" by this directive
    pool = Pool()

（更仔细地研究错误消息，现在我非常确定在声明pool = Pool()后移动runit 也会在Linux上解决它，但包装在__main__修复+使其可移植）

那就是说，请注意您的多处理只是创建一个新进程，因此您最好使用线程池（Threading pool similar to the multiprocessing Pool?）：创建进程的线程，如下所示：

from multiprocessing.pool import ThreadPool # uses threads, not processes import os def runit(cmd): proc = Popen(cmd, shell=True,stdout=PIPE, stderr=PIPE, universal_newlines=True) return proc.stdout.read() it = [] for i in range(1,3): it.append('ls -l') if __name__=="__main__": pool = ThreadPool() # ThreadPool instead of Pool results = pool.map(runit, it) print(results) results = pool.map(runit, it) print(results)

后一种解决方案更轻巧，并且不易出错（多处理是一个难以处理的模块）。您将能够使用对象，共享数据等...而不需要Manager对象，以及其他优点

多处理简单功能不起作用，但原因何在

1 个答案: