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https://issues.apache.org/jira/browse/HBASE-11965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14132287#comment-14132287
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Vladimir Rodionov commented on HBASE-11965:
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{quote}
 All mutations on a region will be blocked until last read lock released. Bad.
{quote}

No, that is not true.  Write locks are only acquired during bulkHFileLoad. 
Anyway, there are still a lot of room for improvement, especially in Gets, 
Multi gets and scan next op.

> Optimize locking in HRegion
> ---------------------------
>
>                 Key: HBASE-11965
>                 URL: https://issues.apache.org/jira/browse/HBASE-11965
>             Project: HBase
>          Issue Type: Bug
>          Components: Performance
>            Reporter: Vladimir Rodionov
>            Assignee: Vladimir Rodionov
>
> Described in this thread:
> http://mail-archives.apache.org/mod_mbox/hbase-dev/201409.mbox/%3CCAAg3a2qmWJtQbdAk7PrX%2BW8SZWxsYhNggM5f2RNkGTXUri34YQ%40mail.gmail.com%3E
> *startRegionOperation* and *closeRegionOperation* in HRegion acquires and 
> releases region-wide lock. The locking happens for every mutation, read and 
> scan next. This is a serious bottleneck if we do:
> * Mutli - get on a same region.
> * Run multiple scanners on same region.
> * Do scan during compaction.
> * Access region simultaneously from different threads (most generic case)



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