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From Aljoscha Krettek <aljos...@apache.org>
Subject Thoughts About Object Reuse and Collection Execution
Date Fri, 27 Feb 2015 14:36:15 GMT
Hello Nation of Flink,
while figuring out this bug:
https://issues.apache.org/jira/browse/FLINK-1569
I came upon some difficulties. The problem is that the
KeyExtractorMappers always
return the same tuple. This is problematic, since Collection Execution
does simply store the returned values in a list. These elements are
not copied before they are stored when object reuse is enabled.
Therefore, the whole list will contain only that one reused element.

I see two options for solving this:
1. Change KeyExtractorMappers to always return a new tuple, thereby
making object-reuse mode in cluster execution useless for key
extractors.

2. Change collection execution mapper to always make copies of the
returned elements. This would make object-reuse in collection
execution pretty much obsolete, IMHO.

How should we proceed with this?

Cheers,
Aljoscha

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