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From "Sean Busbey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-4458) lock contention around configuration settings impacts tablet server performance
Date Thu, 15 Sep 2016 15:22:20 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15493636#comment-15493636
] 

Sean Busbey commented on ACCUMULO-4458:
---------------------------------------

{quote}
bq. It seems like it would be more simple if we just extracted all Accumulo properties (instead
of this reduced list). Is there a big impact on memory for this?
I just can't get over a worry that the HOT_PATH_PROPERTIES will rot and your optimization
will be undone (or less efficient). We don't have that many properties, I think it might be
better long-term to just put(prop.getKey(), null) for all of the Property's that are not explicitly
defined.
{quote}

If we want to do that, it's simpler to just not keep around / use the underlying Hadoop Configuration
object and default to the parent config for anything that's not in the cached hashmap. I'll
push this and then make a follow on to give that a try.

I agree on the general concern for HOT_PATH_PROPERTIES, but I think we need an answer for
regular automated checks for perf regressions with or without it.

Thanks for the feedback!

> 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
>
>
> 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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