与多处理错误的另一个混淆，“模块"对象没有属性“f"

yet another confusion with multiprocessing error, #39;module#39; object has no attribute #39;f#39;(与多处理错误的另一个混淆，“模块对象没有属性“f)

问题描述

我知道这个问题之前已经回答过了，但似乎直接执行脚本python filename.py"是行不通的.我在 SuSE Linux 上安装了 Python 2.6.2.

I know this has been answered before, but it seems that executing the script directly "python filename.py" does not work. I have Python 2.6.2 on SuSE Linux.

代码:

#!/usr/bin/python
# -*- coding: utf-8 -*-
from multiprocessing import Pool
p = Pool(1)
def f(x):
    return x*x
p.map(f, [1, 2, 3])

命令行:

> python example.py
Process PoolWorker-1:
Traceback (most recent call last):
File "/usr/lib/python2.6/multiprocessing/process.py", line 231, in _bootstrap
    self.run()
File "/usr/lib/python2.6/multiprocessing/process.py", line 88, in run
    self._target(*self._args, **self._kwargs)
File "/usr/lib/python2.6/multiprocessing/pool.py", line 57, in worker
    task = get()
File "/usr/lib/python2.6/multiprocessing/queues.py", line 339, in get
    return recv()
AttributeError: 'module' object has no attribute 'f'

推荐答案

重构代码，以便在创建 Pool 实例之前定义 f() 函数.否则worker看不到你的函数.

Restructure your code so that the f() function is defined before you create instance of Pool. Otherwise the worker cannot see your function.

#!/usr/bin/python
# -*- coding: utf-8 -*-

from multiprocessing import Pool

def f(x):
    return x*x

p = Pool(1)
p.map(f, [1, 2, 3])

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