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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4112) Poor performance due to MinC start/stop updates are always hsync'd
Date Tue, 08 Mar 2016 23:33:40 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4112?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15186068#comment-15186068
] 

ASF GitHub Bot commented on ACCUMULO-4112:
------------------------------------------

Github user joshelser commented on the pull request:

    https://github.com/apache/accumulo/pull/79#issuecomment-194023887
  
    :+1: pending some successful ITs.


> Poor performance due to MinC start/stop updates are always hsync'd
> ------------------------------------------------------------------
>
>                 Key: ACCUMULO-4112
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4112
>             Project: Accumulo
>          Issue Type: Bug
>          Components: tserver
>         Environment: Fluo testing on a 20-node cluster
>            Reporter: Eric Newton
>            Assignee: Keith Turner
>            Priority: Critical
>             Fix For: 1.7.2, 1.8.0
>
>         Attachments: HSyncOverheadExperiment.png, MinCFlushPerfTest.java, Sync-Flush-Log-Performance.png
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> [~kturner] writes:
> {quote}
> I was running a Fluo test with 1.8.0-SNAP on my workstation.  My Fluo table had a ton
of tablets.   I was seeing terrible performance.   I started looking at the tserver and noticed
it was always calling hsync.  I tracked down the problem to the fact that when minc start
and stop events are written to the log they are always written w/ sync level.   My poor little
tserver was constantly minor compacting (probably had around 600 tablets that were all being
written to).  
> I changed the test config to create like 15 tablets and the performance was much better.
 All cores were 100% utilized, which was not the case when hsync was always called.
> {quote}



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