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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-3587) Eliminate use of ReadWriteLock in RegionObserver coprocessor invocation
Date Tue, 01 Mar 2011 23:02:36 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13001169#comment-13001169

stack commented on HBASE-3587:

Thanks for filing this Gary.  TRUNK seems broke.  Its burning CPU like crazy.  Perhaps it
is this issue?

> 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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