相关疑难解决方法(0)

我正在使用Python 3.6,并且正在尝试跟随下面网站上的第一个示例(下面的完整代码)并且我得到以下错误:https: //docs.python.org/3.6/library/multiprocessing. HTML

错误信息: AttributeError: module '__main__' has no attribute '__spec__'

完整示例代码:

from multiprocessing import Pool

def f(x):
    return x*x

if __name__ == '__main__':
    with Pool(5) as p:
        print(p.map(f, [1, 2, 3]))

我尝试使用Google搜索并搜索Stack Overflow,但我只发现了另一个此错误的情况并且没有答案.

我已经通过将导入移到顶部声明来解决我的问题，但它让我想知道：为什么我不能使用'__main__'在作为目标的函数中导入的模块multiprocessing？

例如：

import os
import multiprocessing as mp

def run(in_file, out_dir, out_q):
    arcpy.RaterToPolygon_conversion(in_file, out_dir, "NO_SIMPIFY", "Value")
    status = str("Done with "+os.path.basename(in_file))
    out_q.put(status, block=False)

if __name__ == '__main__':
    raw_input("Program may hang, press Enter to import ArcPy...")
    import arcpy

    q = mp.Queue()
    _file = path/to/file
    _dir = path/to/dir
    # There are actually lots of files in a loop to build
    # processes but I just do one for context here
    p = mp.Process(target=run, args=(_file, _dir, q))
    p.start()

# …