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From "Chris Douglas (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-3398) ReduceTask::closestPowerOf2 is inefficient
Date Mon, 19 May 2008 21:21:55 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-3398?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Chris Douglas updated HADOOP-3398:
----------------------------------

    Resolution: Fixed
        Status: Resolved  (was: Patch Available)

I just committed this.

> ReduceTask::closestPowerOf2 is inefficient
> ------------------------------------------
>
>                 Key: HADOOP-3398
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3398
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: mapred
>            Reporter: Chris Douglas
>            Assignee: Chris Douglas
>            Priority: Trivial
>             Fix For: 0.18.0
>
>         Attachments: 3398-0.patch, 3398-1.patch, 3398-2.patch, 3398-3.patch
>
>
> ReduceTask computes the "closest power of 2" using loops
> {code}
> private static int getClosestPowerOf2(int value) {
>   int power = 0;
>   int approx = 1;
>   while (approx < value) {
>     ++power;
>     approx = (approx << 1);
>   }
>   if ((value - (approx >> 1)) < (approx - value)) {
>     --power;
>   }
>   return power;
> }
> {code}
> This could be improved.

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