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Posted to mapreduce-issues@hadoop.apache.org by "Todd Lipcon (JIRA)" <ji...@apache.org> on 2014/07/17 20:21:08 UTC

[jira] [Commented] (MAPREDUCE-5962) Support CRC32C in IFile

    [ https://issues.apache.org/jira/browse/MAPREDUCE-5962?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14065291#comment-14065291 ] 

Todd Lipcon commented on MAPREDUCE-5962:
----------------------------------------

(fwiw this depends on [~james.thomas]'s work to enable native checksumming on byte arrays. So we won't see an immediate benefit, but will once that patch is done)

> Support CRC32C in IFile
> -----------------------
>
>                 Key: MAPREDUCE-5962
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-5962
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: performance, task
>    Affects Versions: 2.5.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>         Attachments: mapreduce-5962.txt
>
>
> Currently, the IFile format used by the MR shuffle checksums all data using the zlib CRC32 polynomial. If we allow use of CRC32C instead, we can get a large reduction in CPU usage by leveraging the native hardware CRC32C implementation (approx half a second of CPU time savings per GB checksummed).



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