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

["Gopal V (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TEZ-1491?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gopal V updated TEZ-1491:
-------------------------

    Attachment: perf-top-counters.png

> 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
>            Reporter: Gopal V
>            Assignee: Gopal V
>         Attachments: 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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