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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1927) [Py] Rework operator distribution
Date Wed, 29 Apr 2015 12:34:07 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1927?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14519269#comment-14519269

ASF GitHub Bot commented on FLINK-1927:

Github user aljoscha commented on the pull request:

    But doesn't this mean that the lambdas now must be stateless, i.e. if a user refers to
some variable outside the lambda this will not be serialised with the closure anymore (because
there is no serialization of the closure anymore).

> [Py] Rework operator distribution
> ---------------------------------
>                 Key: FLINK-1927
>                 URL: https://issues.apache.org/jira/browse/FLINK-1927
>             Project: Flink
>          Issue Type: Improvement
>          Components: Python API
>    Affects Versions: 0.9
>            Reporter: Chesnay Schepler
>            Assignee: Chesnay Schepler
>            Priority: Minor
>             Fix For: 0.9
> Currently, the python operator is created when execution the python plan file, serialized
using dill and saved as a byte[] in the java function. It is then deserialized at runtime
on each node.
> The current implementation is fairly hacky, and imposes certain limitations that make
it hard to work with. Chaining, or generally saving other user-code, always requires a separate
deserialization step after deserializing the operator.
> These issues can be easily circumvented by rebuilding the (python) plan on each node,
instead of serializing the operator. The plan creation is deterministic, and every operator
is uniquely identified by an ID that is already known to the java function.
> This change will allow us to easily support custom serializers.

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