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From "Josh Elser (JIRA)" <j...@apache.org>
Subject [jira] [Created] (ACCUMULO-3957) Consider moving off getContentSummary in the monitor
Date Tue, 11 Aug 2015 00:52:46 GMT
Josh Elser created ACCUMULO-3957:
------------------------------------

             Summary: 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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