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https://issues.apache.org/jira/browse/HBASE-6755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13453749#comment-13453749
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Lars Hofhansl commented on HBASE-6755:
--------------------------------------
Interestingly, if I just try to increment the idGenerator twice the other core
never sees a stale value. This is probably due to ConcurrentHashMap taking out
a memory barrier anyway... Which incidentally makes this whole issue a moot
point.
I'll play a bit more tomorrow and probably close as "Invalid".
> 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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