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https://issues.apache.org/jira/browse/MAPREDUCE-4851?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13511481#comment-13511481
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Radim Kolar commented on MAPREDUCE-4851:
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point of having lifecycle for comparators means that you can do more elaborate
actions in them. They can become 1st class component instead of just mere
helper class for comparing bytes. Most important is to be able to do runtime
link with other components.
why you have lifecycle in mapper/reducer?
> add lifecycle to Comparators
> ----------------------------
>
> Key: MAPREDUCE-4851
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4851
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Reporter: Radim Kolar
> Labels: mrv2
>
> current mapreduce api is using RawComparator interface in:
> setGroupingComparatorClass
> setSortComparatorClass
> This interface has no lifecycle support. I propose to change that methods to
> take argument new class implements RawComparator with setup and cleanup
> methods.
> This will leave existing code with RawComparator alone, Providing some
> backward compatibility.
> new class:
> class SortComparator implements RawComparator
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