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From "Mingjie Lai (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-3587) Eliminate use of ReadWriteLock in RegionObserver coprocessor invocation
Date Tue, 01 Mar 2011 23:20:36 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13001173#comment-13001173
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Mingjie Lai commented on HBASE-3587:
------------------------------------

stack. 
It's been in trunk for a while. Do you see the crazy-CPU-burning recently? From unit tests
or at a cluster? 

> Eliminate use of ReadWriteLock in RegionObserver coprocessor invocation
> -----------------------------------------------------------------------
>
>                 Key: HBASE-3587
>                 URL: https://issues.apache.org/jira/browse/HBASE-3587
>             Project: HBase
>          Issue Type: Improvement
>          Components: coprocessors
>            Reporter: Gary Helmling
>
> Follow-up to a discussion on the dev list: http://search-hadoop.com/m/jOovV1uAJBP
> The CoprocessorHost ReentrantReadWriteLock is imposing some overhead on data read/write
operations, even when no coprocessors are loaded.  Currently execution of RegionCoprocessorHost
pre/postXXX() methods are guarded by acquiring the coprocessor read lock.  This is used to
prevent coprocessor registration from modifying the coprocessor collection while upcall hooks
are in progress.
> On further discussion, and looking at the locking in HRegion, it should be sufficient
to just use a CopyOnWriteArrayList for the coprocessor collection.  We can then remove the
coprocessor lock and eliminate the associated overhead without having to special case the
"no loaded coprocessors" condition.

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