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Date: Thu, 6 Dec 2012 16:37:09 +0000 (UTC)
From: "Radim Kolar (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Message-ID: <JIRA.12619137.1354805797937.768.1354811829491@arcas>
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Subject: [jira] [Commented] (MAPREDUCE-4851) add lifecycle to Comparators
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-4851?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13511499#comment-13511499 ] 

Radim Kolar commented on MAPREDUCE-4851:
----------------------------------------

for example you can not use datagrid in comparator because if you start it in setConf() you can shut it down, which is kinda huge memory leak if JVM reuse is enabled. It will also block JVM exit unless hadoop is using System.exit() call.
                
> 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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