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From "Dave Latham (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-3894) Thread contention over row locks set monitor
Date Tue, 24 May 2011 21:32:47 GMT

     [ https://issues.apache.org/jira/browse/HBASE-3894?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Dave Latham updated HBASE-3894:
-------------------------------

    Attachment: concurrentRowLocks-trunk-2.patch

We rolled this patch on top of 0.90.3 out to production last week.  The Map Reduce jobs that
were causing the contention and region server unavailability are now completing smoothly and
faster.  (Thread dumps of the region server hosting the contended region server show a number
of threads blocked at ReadWriteConsistencyControl.completeMemstoreInsert(line 131).)

I've updated the patch to match the current trunk.  It also removes the lastCompactInfo field
which is no longer used since HBASE-3797 hit trunk.

> 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-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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