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From "Ted Yu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-3894) Thread contention over row locks set monitor
Date Wed, 18 May 2011 23:10:47 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3894?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13035841#comment-13035841
] 

Ted Yu commented on HBASE-3894:
-------------------------------

@Dave:
The introduction of CountDownLatch may increase heap pressure.
Please share what you find in your cluster(s) in this regards.

Thanks

> Thread contention over row locks set monitor
> --------------------------------------------
>
>                 Key: HBASE-3894
>                 URL: https://issues.apache.org/jira/browse/HBASE-3894
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.90.2
>            Reporter: Dave Latham
>            Priority: Blocker
>             Fix For: 0.90.4
>
>         Attachments: concurrentRowLocks-2.patch, concurrentRowLocks-trunk.patch, regionserver_rowLock_set_contention.threads.txt
>
>
> HRegion maintains a set of row locks.  Whenever any thread attempts to lock or release
a row it needs to acquire the monitor on that set.  We've been encountering cases with 30
handler threads all contending for that monitor, blocked progress on the region server.  Clients
timeout, and retry making it worse, and the region server stops responding to new clients
almost entirely.

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