[jira] [Commented] (ACCUMULO-4112) Poor performance due to MinC start/stop updates are always hsync'd

["Christopher Tubbs (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ACCUMULO-4112?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15112646#comment-15112646 ] 

Christopher Tubbs commented on ACCUMULO-4112:
---------------------------------------------

Updated the subject line to include "poor performance" to give additional context to the current "Cannot Reproduce" status. (Otherwise, it reads like the start/stop updates being hsync'd couldn't be reproduced, which wouldn't be accurate.)

> 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: Eric Newton
>            Priority: Minor
>         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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