[jira] Resolved: (HADOOP-2959) When a mapper needs to run a combiner, it should create one and reuse it, instead of creating one per partition per spill

["Owen O'Malley (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-2959?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Owen O'Malley resolved HADOOP-2959.
-----------------------------------

    Resolution: Won't Fix

This is a feature, not a bug. The reduce (and combiner) are guaranteed they will get the inputs in sorted order. If you re-use a combiner, that is no longer true. If initialization is expensive, move it to an external/static class.

> When a mapper needs to run a combiner, it should create one and reuse it, instead of creating one per partition per spill
> -------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-2959
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2959
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.16.0
>            Reporter: Runping Qi
>


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