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Date: Fri, 6 Jul 2012 23:59:33 +0000 (UTC)
From: "Andrew Purtell (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Comment Edited] (HBASE-6346) Metrics updating may be using
 excessive CPU
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    [ https://issues.apache.org/jira/browse/HBASE-6346?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13408463#comment-13408463 ] 

Andrew Purtell edited comment on HBASE-6346 at 7/6/12 11:57 PM:
----------------------------------------------------------------

See attached graph.gif what CPU use on the cluster looks like. Nothing should be running, this is a Hadoop+HBase cluster started up and left alone. 'top' on the hosts shows all CPU time used by the JVM running the regionserver.

Attached as runnable_cpu_profile.png is a snapshot of what jprofiler sees of a 2.0.1+0.94.1 HBase process started in-tree as './bin/hbase master start'. I've also attached a stack dump so you can see it is doing "nothing".

Edit: I haven't missed that most of that time is system time. Wonder what is up with that.
                
      was (Author: apurtell):
    See attached graph.gif what CPU use on the cluster looks like. Nothing should be running, this is a Hadoop+HBase cluster started up and left alone. 'top' on the hosts shows all CPU time used by the JVM running the regionserver.

Attached as runnable_cpu_profile.png is a snapshot of what jprofiler sees of a 2.0.1+0.94.1 HBase process started in-tree as './bin/hbase master start'. I've also attached a stack dump so you can see it is doing "nothing".
                  
> Metrics updating may be using excessive CPU
> -------------------------------------------
>
>                 Key: HBASE-6346
>                 URL: https://issues.apache.org/jira/browse/HBASE-6346
>             Project: HBase
>          Issue Type: Bug
>         Environment: Hadoop 2.0.1-alpha, HBase 0.94.1-SNAPSHOT
>            Reporter: Andrew Purtell
>         Attachments: graph.gif, jstack.txt, runnable_cpu_profile.png
>
>
> I've only started looking at this but became concerned when a completely quiescent cluster loads up 20% CPU (system+user) once HBase comes up.

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