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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3957) Consider moving off getContentSummary in the monitor
Date Wed, 12 Aug 2015 20:54:45 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14694153#comment-14694153
] 

Josh Elser commented on ACCUMULO-3957:
--------------------------------------

Since we're calling getContentSummary on "/" we have to assume any other components use of
HDFS, not just how we use HDFS, is called into question. I'm guessing that we ourselves aren't
misusing HDFS itself. We figured that out a long time ago.

> Consider moving off getContentSummary in the monitor
> ----------------------------------------------------
>
>                 Key: ACCUMULO-3957
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-3957
>             Project: Accumulo
>          Issue Type: Bug
>          Components: monitor
>            Reporter: Josh Elser
>            Assignee: Josh Elser
>            Priority: Critical
>             Fix For: 1.6.4, 1.7.1, 1.8.0, 1.5.4
>
>
> Recently heard about an issue where a large Hadoop installation which had Accumulo running
was experiencing long pauses in the Namenode. Inspecting NN audit logs, it was found that
the user running Accumulo issues a {{getContentSummary("/")}} call just before the NN pauses
were experienced.
> In {{DefaultServlet.java}}, we use this call to compute the total HDFS disk usage and
present a ratio of space that Accumulo uses relative to the total available space.
> It's still unclear why this was causing issues in this case (as this operation should
only be acquiring a read-lock in the namenode), it was recommended to me that Accumulo use
the JMX metrics for the NN instead of making this call.



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