在 python 中尝试使用多处理运行循环时出错

Question

I am trying to run a function in a loop many times using parallel multiprocessing.我正在尝试使用并行多处理在循环中多次运行 function。

When I run this simple code:当我运行这个简单的代码时：

import time
from multiprocessing import Pool

def heavy_processing(number):
    time.sleep(0.05)  # simulate a long-running operation
    output = number + 1
    return output

with Pool(4) as p:
    numbers = list(range(0, 1000))    
    results = p.map(heavy_processing, numbers)

I get the following error:我收到以下错误：

Process SpawnPoolWorker-1:
Traceback (most recent call last):
  File "C:\ProgramData\Miniconda3\lib\multiprocessing\process.py", line 315, in _bootstrap
    self.run()
  File "C:\ProgramData\Miniconda3\lib\multiprocessing\process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "C:\ProgramData\Miniconda3\lib\multiprocessing\pool.py", line 114, in worker
    task = get()
  File "C:\ProgramData\Miniconda3\lib\multiprocessing\queues.py", line 367, in get
    return _ForkingPickler.loads(res)
AttributeError: Can't get attribute 'heavy_processing' on <module '__main__' (built-in)>

I'm not sure why, since I pretty much pulling this example straight from other sources.我不确定为什么，因为我几乎直接从其他来源提取了这个示例。 Any idea what's going on?知道发生了什么事吗？

Answer 1

You have to run the multiprocessing code always under the if __name__ == '__main__': or else it doesn't work.您必须始终在if __name__ == '__main__':下运行多处理代码，否则它不起作用。 If you see the last line of your cmd you can see AttributeError: Can't get attribute 'heavy_processing' on <module ' main ' (built-in)> which specifies that it couldn't find 'heavy_processing' on ' main '如果您看到 cmd 的最后一行，您会看到 AttributeError: Can't get attribute 'heavy_processing' on <module ' main ' (built-in)> 指定它在 ' main ' 上找不到 'heavy_processing'

Full Code完整代码

import time
from multiprocessing import Pool


def heavy_processing(number):
    time.sleep(0.05)  # simulate a long-running operation
    output = number + 1
    print(output)
    return output


if __name__ == '__main__':
    with Pool(4) as p:
        numbers = list(range(0, 1000))
        results = p.map(heavy_processing, numbers)

Output Output

Hope this helps.希望这可以帮助。 Happy Coding:)快乐编码:)

在 python 中尝试使用多处理运行循环时出错

问题描述

1 个解决方案

解决方案1
0 已采纳 2022-12-07 04:42:00

在 python 中尝试使用多处理运行循环时出错

问题描述

1 个解决方案

解决方案1 0 已采纳 2022-12-07 04:42:00

解决方案1
0 已采纳 2022-12-07 04:42:00