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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4458) lock contention around configuration settings impacts tablet server performance
Date Thu, 15 Sep 2016 19:55:20 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15494351#comment-15494351
] 

Josh Elser commented on ACCUMULO-4458:
--------------------------------------

bq. Is there a reason we need the HOT_PATHS_PROPERTIES at all? Why would we ever go back to
getXmlConfig()? Why not just always default to the parent (DefaultConfiguration) when it doesn't
exist in SiteConfiguration's static set of props on first load?

I think I had asked this same question. Is this missing from the earlier discussion?

bq. Also, containsKey(key) followed by get(key) is unnecessarily inefficient. Just do a get,
and check if it's null.

Another thing I had noticed, but I don't think that the semantics are the same because he
loads a null value into the map. I believe what he has presently is correct.

> lock contention around configuration settings impacts tablet server performance
> -------------------------------------------------------------------------------
>
>                 Key: ACCUMULO-4458
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-4458
>             Project: Accumulo
>          Issue Type: Bug
>          Components: tserver
>    Affects Versions: 1.7.1, 1.8.0
>            Reporter: Sean Busbey
>            Assignee: Sean Busbey
>            Priority: Critical
>             Fix For: 1.7.3, 1.8.1, 2.0.0
>
>         Attachments: ACCUMULO-4458-1.7.v1.patch
>
>          Time Spent: 50m
>  Remaining Estimate: 0h
>
> While investigating a pretty severe performance regression comparing YCSB against 1.6
and 1.7, I found a fair bit of lock contention around getting configuration values. This was
improved by ACCUMULO-4388, but various threads eventually all started contending on the configuration
values expected from the site xml files.



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