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Posted to jira@arrow.apache.org by "BinbinLiang (Jira)" <ji...@apache.org> on 2020/11/21 13:50:00 UTC

[jira] [Commented] (ARROW-10676) [Python] pickle error occurs when using pyarrow._plasma.PlasmaClient with multiprocess on mac (python3.8.5)

    [ https://issues.apache.org/jira/browse/ARROW-10676?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17236670#comment-17236670 ] 

BinbinLiang commented on ARROW-10676:
-------------------------------------

And  the error does not occur, when I change 'multiprocessing.context.Process' to 'multiprocess.context.Process' which use *dill* to serialize.

> [Python] pickle error occurs when using pyarrow._plasma.PlasmaClient with multiprocess on mac (python3.8.5)
> -----------------------------------------------------------------------------------------------------------
>
>                 Key: ARROW-10676
>                 URL: https://issues.apache.org/jira/browse/ARROW-10676
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>    Affects Versions: 0.17.1, 2.0.0
>         Environment: OS: mac os catalina 10.15.6;
> Python version: python3.8.5;
>            Reporter: BinbinLiang
>            Priority: Major
>
> * The environment is:
>  ** OS: mac os catalina 10.15.6;
>  ** {color:#FF0000}Python version: python3.8.5;{color}
>  * {color:#ff0000}It's ok, when use python3.7(3.7.2 or 3.7.3) or python3.6(3.6.8).
> The error occurs only in python3.8.5.{color}
>  * When I use 'pyarrow._plasma.PlasmaClient' in the 'multiprocessing.context.Process', the error occurs.
>  ** First, I have a subclass of 'multiprocessing.context.Process', named Executor;
> The defined code like this: 'class Executor(Process):' .
>  ** And then, I create a 'PlasmaClient' object in the '__init__' function of 'class Executor' .
>  ** Finally, I new a 'Executor' object, and call the 'start()' function. 
>  * The detail informations of traceback are as follows:
>  Traceback (most recent call last):
>  File "/Users/liangbinbin/PycharmProjects/waimai_data_cubeinsight/python/taf/server/taf_server.py", line 100, in LaunchExecutor
>  executor.start()
>  File "/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/process.py", line 121, in start
>  self._popen = self._Popen(self)
>  File "/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/context.py", line 224, in _Popen
>  return _default_context.get_context().Process._Popen(process_obj)
>  File "/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/context.py", line 284, in _Popen
>  return Popen(process_obj)
>  File "/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 32, in __init__
>  super().__init__(process_obj)
>  File "/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/popen_fork.py", line 19, in __init__
>  self._launch(process_obj)
>  File "/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/popen_spawn_posix.py", line 47, in _launch
>  reduction.dump(process_obj, fp)
>  File {color:#FF0000}"/Users/liangbinbin/Applications/anaconda3/envs/python3_8/lib/python3.8/multiprocessing/reduction.py", line 60, in dump{color}
>  {color:#FF0000}ForkingPickler(file, protocol).dump(obj){color}
>  {color:#FF0000}File "stringsource", line 2, in *pyarrow._plasma.PlasmaClient.__reduce_cython__*{color}
>  TypeError: no default __reduce__ due to non-trivial __cinit__



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