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Re: Using Pool map with a method of a class and a list

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On Tuesday, 6 August 2013 18:12:26 UTC+1, Luca Cerone  wrote:
> Hi guys,
> 
> I would like to apply the Pool.map method to a member of a class.
> 
> 
> 
> Here is a small example that shows what I would like to do:
> 
> 
> 
> from multiprocessing import Pool
> 
> 
> 
> class A(object):
> 
>    def __init__(self,x):
> 
>        self.value = x
> 
>    def fun(self,x):
> 
>        return self.value**x
> 
> 
> 
> 
> 
> l = range(10)
> 
> 
> 
> p = Pool(4)
> 
> 
> 
> op = p.map(A.fun,l)
> 
> 
> 
> #using this with the normal map doesn't cause any problem
> 
> 
> 
> This fails because it says that the methods can't be pickled.
> 
> (I assume it has something to do with the note in the documentation: "functionality within this package requires that the __main__ module be importable by the children.", which is obscure to me).
> 
> 
> 
> I would like to understand two things: why my code fails and when I can expect it to fail? what is a possible workaround?
> 
> 
> 
> Thanks a lot in advance to everybody for the help!
> 
> 
> 
> Cheers,
> 
> Luca



On Tuesday, 6 August 2013 18:12:26 UTC+1, Luca Cerone  wrote:
> Hi guys,
> 
> I would like to apply the Pool.map method to a member of a class.
> 
> 
> 
> Here is a small example that shows what I would like to do:
> 
> 
> 
> from multiprocessing import Pool
> 
> 
> 
> class A(object):
> 
>    def __init__(self,x):
> 
>        self.value = x
> 
>    def fun(self,x):
> 
>        return self.value**x
> 
> 
> 
> 
> 
> l = range(10)
> 
> 
> 
> p = Pool(4)
> 
> 
> 
> op = p.map(A.fun,l)
> 
> 
> 
> #using this with the normal map doesn't cause any problem
> 
> 
> 
> This fails because it says that the methods can't be pickled.
> 
> (I assume it has something to do with the note in the documentation: "functionality within this package requires that the __main__ module be importable by the children.", which is obscure to me).
> 
> 
> 
> I would like to understand two things: why my code fails and when I can expect it to fail? what is a possible workaround?
> 
> 
> 
> Thanks a lot in advance to everybody for the help!
> 
> 
> 
> Cheers,
> 
> Luca

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Thread

Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-06 10:12 -0700
  Re: Using Pool map with a method of a class and a list Chris Angelico <rosuav@gmail.com> - 2013-08-06 18:38 +0100
    Re: Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-06 12:42 -0700
      Re: Using Pool map with a method of a class and a list Joshua Landau <joshua@landau.ws> - 2013-08-07 07:48 +0100
        Re: Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-07 01:33 -0700
          Re: Using Pool map with a method of a class and a list Joshua Landau <joshua@landau.ws> - 2013-08-07 10:47 +0100
            Re: Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-07 03:10 -0700
              Re: Using Pool map with a method of a class and a list Joshua Landau <joshua@landau.ws> - 2013-08-07 12:53 +0100
                Re: Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-07 15:26 -0700
                Re: Using Pool map with a method of a class and a list Joshua Landau <joshua@landau.ws> - 2013-08-07 23:49 +0100
              Re: Using Pool map with a method of a class and a list Peter Otten <__peter__@web.de> - 2013-08-07 16:46 +0200
              Re: Using Pool map with a method of a class and a list Joshua Landau <joshua@landau.ws> - 2013-08-07 16:52 +0100
              Re: Using Pool map with a method of a class and a list Peter Otten <__peter__@web.de> - 2013-08-07 18:15 +0200
                Re: Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-07 16:31 -0700
  Re: Using Pool map with a method of a class and a list Luca Cerone <luca.cerone@gmail.com> - 2013-08-06 12:37 -0700

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