Question

我第一次在python3中使用多处理。以下是我要实现的内容：

import concurrent
t = concurrent.futures.ProcessPoolExecutor(4)
g = t.map(lambda x:10*x, range(10))

它正在抛出错误：

File "/usr/local/Cellar/python3/3.4.3/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/queues.py", line 242, in _feed
    obj = ForkingPickler.dumps(obj)
  File "/usr/local/Cellar/python3/3.4.3/Frameworks/Python.framework/Versions/3.4/lib/python3.4/multiprocessing/reduction.py", line 50, in dumps
    cls(buf, protocol).dump(obj)
_pickle.PicklingError: Can't pickle <function <lambda> at 0x102f03730>: attribute lookup <lambda> on __main__ failed

每次都挂掉。

Answer 1

传递给t.map needs to be picklable的函数。匿名函数（即lambda函数）are not picklable - 至少not by default。要修复，请在全局命名空间中定义函数：

import concurrent.futures as CF
def func(x):
    return 10*x

if __name__ == '__main__':
    with CF.ProcessPoolExecutor(4) as t:
        g = t.map(func, range(10))
        print(list(g))
        # [0, 10, 20, 30, 40, 50, 60, 70, 80, 90]

python3中的多处理无法正常工作

1 个答案: