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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-2533) [hbase] Performance: Scanning, just creating MapWritable in next consumes >20% CPU
Date Sun, 06 Jan 2008 07:28:34 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-2533?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

stack updated HADOOP-2533:
--------------------------

    Attachment: dirty.patch

Attached dirty patch -- it needs a bunch of work to make it committable -- shrinks MapWritable
CPU usage over a PerformanceEvaluation run from 22.9% of all CPU used down to 0.8%.  It uses
a dumber MapWritable -- one that has static maps of classes to codes -- and one that is more
friendly to hbase;  it has been primed with hbase type (they have to be dynamically 'added'
to each new instantiation of the hadoop.io version of MapWritable).

> [hbase] Performance: Scanning, just creating MapWritable in next consumes >20% CPU
> ----------------------------------------------------------------------------------
>
>                 Key: HADOOP-2533
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2533
>             Project: Hadoop
>          Issue Type: Improvement
>          Components: contrib/hbase
>            Reporter: stack
>            Priority: Minor
>         Attachments: dirty.patch
>
>
> Every call to HScanner.next creates an instance of MapWritable.  MapWritables are expensive.
 Watching a scan run in the profiler, the setup of the MapWritable -- filling out the idToClassMap
and classToIdMap -- consumes 20% of all CPU.

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