Can't pickle <type 'instancemethod'> when using multiprocessing Pool.map()

問題：

I'm trying to use multiprocessing 's Pool.map() function to divide out work simultaneously.我正在嘗試使用multiprocessing的Pool.map()函數來同時劃分工作。 When I use the following code, it works fine:當我使用以下代碼時，它工作正常：

import multiprocessing

def f(x):
    return x*x

def go():
    pool = multiprocessing.Pool(processes=4)        
    print pool.map(f, range(10))


if __name__== '__main__' :
    go()

However, when I use it in a more object-oriented approach, it doesn't work.但是，當我以更面向對象的方法使用它時，它不起作用。 The error message it gives is:它給出的錯誤信息是：

PicklingError: Can't pickle <type 'instancemethod'>: attribute lookup
__builtin__.instancemethod failed

This occurs when the following is my main program:當以下是我的主程序時會發生這種情況：

import someClass

if __name__== '__main__' :
    sc = someClass.someClass()
    sc.go()

and the following is my someClass class:以下是我的someClass類：

import multiprocessing

class someClass(object):
    def __init__(self):
        pass

    def f(self, x):
        return x*x

    def go(self):
        pool = multiprocessing.Pool(processes=4)       
        print pool.map(self.f, range(10))

Anyone know what the problem could be, or an easy way around it?任何人都知道問題可能是什麼，或者解決它的簡單方法？

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解決方案：

參考一： https://en.stackoom.com/question/7cfm
參考二： https://stackoom.com/question/7cfm