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https://issues.apache.org/jira/browse/HBASE-6755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13453732#comment-13453732
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Lars Hofhansl commented on HBASE-6755:
--------------------------------------
Just did a quick test (on my poor 2 core laptop): Ran PE with RandomWrite with
50 Threads (nomapred, ROWS=5000). I added logging to the case where we have to
reset the "idGenerator" from the random number. With this patch I find that it
happened 10 times, without the patch it did not happen at all. With more cores
this effect will be more pronounced - I'll try tomorrow on my work desktop with
12 HW threads (6 cores, 2 hyper threads per core).
> HRegion.internalObtainRowLock uses unecessary AtomicInteger
> -----------------------------------------------------------
>
> Key: HBASE-6755
> URL: https://issues.apache.org/jira/browse/HBASE-6755
> Project: HBase
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Fix For: 0.96.0, 0.94.3
>
> Attachments: 6755-0.96.txt
>
>
> I was looking at HBase's implementation of locks and saw that is
> unnecessarily uses an AtomicInteger to obtain a unique lockid.
> The observation is that we only need a unique one and don't care if we happen
> to skip one.
> In a very unscientific test I saw the %system CPU reduced when the
> AtomicInteger is avoided.
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