[IPython-User] parallel execution with multiprocessing vs. ipcluster

Johann Rohwer jr@sun.ac...
Mon Sep 3 04:52:49 CDT 2012

To follow up on my own post:

On Thursday 30 August 2012 22:10:22 Johann Rohwer wrote:
> Interestingly, the test script using multiprocessing works fine when
> executed within IPython (this is just the plain ipython shell, not
> ipcluster!), but fails when called with straight python, with the
> following traceback:
> Exception in thread Thread-2:
> Traceback (most recent call last):
>   File "/usr/lib/python2.7/threading.py", line 551, in
> __bootstrap_inner
>     self.run()
>   File "/usr/lib/python2.7/threading.py", line 504, in run
>     self.__target(*self.__args, **self.__kwargs)
>   File "/usr/lib/python2.7/multiprocessing/pool.py", line 319, in
> _handle_tasks
>     put(task)
> PicklingError: Can't pickle <type 'code'>: attribute lookup
> __builtin__.code failed

It turns out I needed the codeutil module that is shipped in 
IPython.utils in order to pickle code objects. Obviously ipython loads 
this by default during its startup, but it is not imported in the 
regular python interpreter. Once I copied that file into my own 
application and imported it in its __init__.py, then everything works 

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