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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 00:32:20 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-4458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15491890#comment-15491890
] 

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

{quote}
bq. Right now I do extract all of the properties that are set
Ahh, apologies. I see this now. That leads me to wonder...
{code}
-    String value = getXmlConfig().get(key);
+    /* Check the available-on-load configs and fall-back to the possibly-update Configuration
object. */
+    String value = staticConfigs.containsKey(key) ? staticConfigs.get(key) : getXmlConfig().get(key);
{code}
Why can't this just be String value = staticConfigs.get(key) then? We know that we have an
explicit Accumulo config key already (given the method signature). Am I missing something
else?
{quote}

SiteConfiguration has a {{set}} method that allows folks to add additional configuration keys
to the underlying Hadoop Configuration object after instantiation. Any calls to {{set}} won't
be reflected in {{staticConfigs}}, because they're read-only after instantiation of SiteConfiguration
so that concurrent access can be safe.

> 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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