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From "Devaraj Das (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-2399) Input key and value to combiner and reducer should be reused
Date Wed, 20 Feb 2008 13:53:48 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-2399?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12570688#action_12570688
] 

Devaraj Das commented on HADOOP-2399:
-------------------------------------

+1 (although it would be nice to have benchmark figures)

> Input key and value to combiner and reducer should be reused
> ------------------------------------------------------------
>
>                 Key: HADOOP-2399
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2399
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.15.1
>            Reporter: Owen O'Malley
>            Assignee: Owen O'Malley
>             Fix For: 0.17.0
>
>         Attachments: 2399-3.patch, reuse-obj-2.patch, reuse-obj.patch
>
>
> Currently, the input key and value are recreated on every iteration for input to the
combiner and reducer. It would speed up the system substantially if we reused the keys and
values. The down side of doing it, is that it may break applications that count on holding
references to previous keys and values, but I think it is worth doing.

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