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From "Christopher Tubbs (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-3957) Consider moving off getContentSummary in the monitor
Date Wed, 12 Aug 2015 20:51:45 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-3957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14694146#comment-14694146
] 

Christopher Tubbs commented on ACCUMULO-3957:
---------------------------------------------

Am I understanding it correctly, that that is due to large directories (directories with many
files)? If so, could this problem be exacerbated by too frequent flushing of tables (perhaps
in combination with too large a compaction ratio), causing many small files?

> 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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