所有示例并发.futures 代码均因“BrokenProcessPool”而失败

在创建我需要的实际应用程序之前，我试图对此有一个基本的了解。我最近从 2.7 升级到 3.3。

直接复制粘贴这段代码来自 python 文档失败了，一个稍微简单的例子也是如此here.

这是我的代码，源自第二个示例：

import concurrent.futures

nums = [1,2,3,4,5,6,7,8,9,10]

def f(x):
    return x * x

# Make sure the map and function are working
print([val for val in map(f, nums)])

# Test to make sure concurrent map is working
with concurrent.futures.ProcessPoolExecutor() as executor:
    for item in executor.map(f, nums):
        print(item)

这是输出：

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
Traceback (most recent call last):
  File "<string>", line 420, in run_nodebug
  File "<module1>", line 13, in <module>
  File "C:\Python33\lib\concurrent\futures\_base.py", line 546, in result_iterator
    yield future.result()
  File "C:\Python33\lib\concurrent\futures\_base.py", line 399, in result
    return self.__get_result()
  File "C:\Python33\lib\concurrent\futures\_base.py", line 351, in __get_result
    raise self._exception
concurrent.futures.process.BrokenProcessPool: A process in the process pool was terminated abruptly while the future was running or pending.

我怎样才能让这段代码按预期工作？我希望这些示例能够开箱即用。

这是我的错，原因有二：

1. 该代码不受保护，即没有if __name__
2. 看起来奇怪的 Traceback 是因为文件没有保存。以前从未给我带来过问题，但在这种情况下却出现了。

纠正both其中修复了错误。

最终测试代码：

import concurrent.futures

nums = [1,2,3,4,5,6,7,8,9,10]

def f(x):
    return x * x
def main():
    # Make sure the map and function are working
    print([val for val in map(f, nums)])

    # Test to make sure concurrent map is working
    with concurrent.futures.ProcessPoolExecutor() as executor:
        print([val for val in executor.map(f, nums)])

if __name__ == '__main__':
    main()

输出，如预期：

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]