[jira] [Commented] (TEZ-1491) Tez reducer-side merge's counter update is slow

["Hitesh Shah (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-1491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15009706#comment-15009706 ] 

Hitesh Shah commented on TEZ-1491:
----------------------------------

[~rajesh.balamohan] review please?

> Tez reducer-side merge's counter update is slow
> -----------------------------------------------
>
>                 Key: TEZ-1491
>                 URL: https://issues.apache.org/jira/browse/TEZ-1491
>             Project: Apache Tez
>          Issue Type: Bug
>    Affects Versions: 0.6.0, 0.7.0, 0.8.0-alpha
>            Reporter: Gopal V
>            Assignee: Gopal V
>              Labels: Performance
>         Attachments: TEZ-1491.1.patch, perf-top-counters.png
>
>
> TezMerger$MergeQueue::next() shows up in profiles due a synchronized block in a tight loop.
> Part of the slow operation was due to DataInputBuffer issues identified earlier in HADOOP-10694, but along with that approx 11% of my lock prefix calls were originating from the following line.
> {code}
>       mergeProgress.set(totalBytesProcessed * progPerByte);
> {code}
> in two places within the core loop.
> !perf-top-counters.png!



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