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Posted to mapreduce-dev@hadoop.apache.org by "Harsh J (Resolved) (JIRA)" <ji...@apache.org> on 2012/01/16 09:59:40 UTC
[jira] [Resolved] (MAPREDUCE-239) Attribute to mark Mappers and
Reducers as side-effect free
[ https://issues.apache.org/jira/browse/MAPREDUCE-239?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Harsh J resolved MAPREDUCE-239.
-------------------------------
Resolution: Won't Fix
I think this is pretty much covered by map and reduce speculative option separation.
> Attribute to mark Mappers and Reducers as side-effect free
> ----------------------------------------------------------
>
> Key: MAPREDUCE-239
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-239
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: Owen O'Malley
>
> There should be an annotation to mark Mapper and Reducer classes as side-effect free. This annotation could then be used to disable speculative execution for such classes. Furthermore, defining a class without the NoSideEffect attribute as a combiner would be a run-time error.
> @NoSideEffects
> class MyMapper extends MapReduceBase implements Mapper { ... }
> would declare that MyMapper may be run speculatively.
> @NoSideEffects
> class MyReducer extends MapReduceBase implements Reducer { ...}
> declares that MyReducer can be run speculative and as a combiner.
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