[jira] [Commented] (TEZ-1593) Refactor PipelinedSorter to remove all MMAP based ByteBuffer references

["Rajesh Balamohan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-1593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14276348#comment-14276348 ] 

Rajesh Balamohan commented on TEZ-1593:
---------------------------------------

WIP patch needs a rebase to master?

> Refactor PipelinedSorter to remove all MMAP based ByteBuffer references
> -----------------------------------------------------------------------
>
>                 Key: TEZ-1593
>                 URL: https://issues.apache.org/jira/browse/TEZ-1593
>             Project: Apache Tez
>          Issue Type: Bug
>    Affects Versions: 0.6.0
>            Reporter: Gopal V
>            Assignee: Gopal V
>              Labels: Performance
>         Attachments: TEZ-1593.1.patch, TEZ-1593.2-WIP.patch
>
>
> The current implementation of PipelinedSorter has a slow section which revolves around key comparisons - this was relevant when the implementation used direct byte buffers to back the kvbuffer.
> {code}
>       kvbuffer.position(istart);
>       kvbuffer.get(ki, 0, ilen);
>       kvbuffer.position(jstart);
>       kvbuffer.get(kj, 0, jlen);
>       // sort by key
>       final int cmp = comparator.compare(ki, 0, ilen, kj, 0, jlen);
> {code}
> The kvbuffer.get into the arrays ki and kj are the slowest part of the comparator operation.



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