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From "Keith Turner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4112) MinC start/stop updates are always hsync'd
Date Tue, 19 Jan 2016 19:26:39 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4112?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15107253#comment-15107253
] 

Keith Turner commented on ACCUMULO-4112:
----------------------------------------

I was using 1.8.0-SNAPSHOT (an older version, I have a branch for ACCUMULO-4066 that I have
not rebased in while).  Looking at the attached test one difference with my scenarion is it
uses BatchWriter.  Fluo uses ConditionalWriter and BatchWriter.  The ConditionalWriter will
be much more sensitive to these pauses.  

> 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: Eric Newton
>            Priority: Minor
>         Attachments: MinCFlushPerfTest.java
>
>
> [~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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