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https://issues.apache.org/jira/browse/MRUNIT-165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13509810#comment-13509810
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Yoni Ben-Meshulam commented on MRUNIT-165:
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Awesome. Thanks Dave.
> MapReduceDriver calls Mapper#cleanup for each input instead of once
> -------------------------------------------------------------------
>
> Key: MRUNIT-165
> URL: https://issues.apache.org/jira/browse/MRUNIT-165
> Project: MRUnit
> Issue Type: Bug
> Affects Versions: 0.9.0
> Reporter: Yoni Ben-Meshulam
> Assignee: Dave Beech
> Fix For: 1.0.0
>
> Attachments: reproduce_MRUNIT-165.patch
>
>
> MapReduceDriver calls the Mapper#run method for each input, causing the
> Mapper#cleanup method to be called multiple times.
> I believe this is a bug, since the contract in MapReduce is that, for a
> single Mapper instance, the Mapper#cleanup method is only called once after
> all inputs to that mapper have been processed. I might be mistaken in my
> assumption here.
> This would not be an issue, were it not for the fact that MapReduceDriver has
> only a single instance of Mapper.
> One solution might be to pass the Mapper _class_ into the MapReduceDriver and
> create a new instance for each input. Another solution might be to call the
> MapDriver with multiple inputs (which AFAIK is not possible).
> See attached patch for an example of a stateful mapper and a test which fails
> due to the bug.
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