[IPython-dev] [parallel] issue when executing 'import pandas as pd' on engine

Francesco Montesano franz.bergesund@gmail....
Tue Sep 17 04:26:43 CDT 2013


Dear Min,

Thanks to the notebook I've found the problem:
the engines (at a certain point) execute the only startup script that I
have (where I call `plt.ion()` see the notebook) but apparently ignores the
ipython_configure.py.

Here is a notebook that show the problem with some more explanation:
http://nbviewer.ipython.org/6592051

I did use the same config files and startup scripts in ipy v0.13, with the
same parallel code and never had the issue.
When I start a console ipy is initialised correctly and `plt.ion()` called
without problems.

If you need anything else let me know,

Fra


2013/9/16 Francesco Montesano <franz.bergesund@gmail.com>

> These codes of mine can be few hundred lines and depend upon other 2 or 3
> modules that I have put together.
>
> If the problem is where I think it is, I might be able to write a
> standalone program (maybe in a notebook). Stay tuned :D
>
> Fra
>
>
>
>
>
> 2013/9/16 MinRK <benjaminrk@gmail.com>
>
>> Cn you please share your whole code?
>>
>>
>> On Mon, Sep 16, 2013 at 9:03 AM, Francesco Montesano <
>> franz.bergesund@gmail.com> wrote:
>>
>>> Dear all,
>>>
>>> I'm having an issue with the parallel (v1.1.0, under python 2.7).
>>>
>>> Some time ago I did build a number of python codes to manipulate
>>> catalogues.
>>> I can have either thousands of small file or few possibly huge file.
>>> So I've written my codes such that I can chose from command whether to
>>> use any of the two.
>>>
>>> Typically my codes have the following structure:
>>>
>>> import numpy as np
>>>> import pandas as pd
>>>> def parse(...):  #argparse
>>>>     ....
>>>> def to_do(fname,...):  #function(s) that do what I need
>>>>     ....
>>>> if __name__=='__main__':
>>>>     args = parse(...)
>>>>     if args.paralell == False:
>>>>          for fn in file_name_list:
>>>>               to_do(fn, ...)
>>>
>>>      else:  #execute in parallel
>>>
>>>          parallel_env = Lbv()       # custom class that init a load
>>>> ballance view
>>>
>>>          imports = ['import numpy as np', 'import pandas as pd']
>>>
>>>          parallel_env.exec_on_engine(imports) # execute the above
>>>> strings on all engines (direct view)
>>>
>>>          #execute in parallel
>>>
>>>          runs = [parallel_env.apply(to_do, os.path.abspath(fn), ...) for
>>>> fn in file_name_list]
>>>
>>>
>>>
>>> I build the whole parallel dispatching against ipython 0.13 and
>>> everything worked fine.
>>> But today I've tried to run one of my scripts enabling parallel and got
>>> the following error
>>>
>>>
>>>>   File "code.py", line XXX, in <module>
>>>>     parallel_env.exec_on_engine(imports)
>>>>   File "XXX/ipython_parallel.py", line 86, in exec_on_engine
>>>>     e.raise_exception()
>>>>   File
>>>> "XXX.local/lib/python2.7/site-packages/IPython/parallel/error.py", line
>>>> 199, in raise_exception
>>>>     raise RemoteError(en, ev, etb, ei)
>>>> RemoteError: NameError(name 'plt' is not defined)
>>>
>>>
>>> The only thing that uses matplotlib is pandas, and modifying
>>>
>>>  imports = ['import numpy as np', 'import matplotlib.pyplot as plt',
>>>> 'import pandas as pd']
>>>
>>>
>>> seems to solve the problem (although at least in one case the first call
>>> of my code crashed with the error and the second went through).
>>>
>>> If I run my code without requiring the ipy parallel I don't have any
>>> problem with 'plt'
>>>
>>> I guess that this is a bug. But I still haven't understood how to debug
>>> what happens on the engines, so I can't give more details.
>>> Any clues?
>>>
>>> If needed I can load my 'ipython_parallel.py' module in gist/github
>>>
>>> Cheers,
>>>
>>> Fra
>>>
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>>>
>>>
>>
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