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https://issues.apache.org/jira/browse/HBASE-15716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15260518#comment-15260518
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Lars Hofhansl commented on HBASE-15716:
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Yeah, I think that should work.
Was thinking about the sorting as well (by a heap maybe), but the enumeration
happens rarely for compactions or flushed (well and for some reason in
Increment and Append). Would't help with the locking problem.
> HRegion#RegionScannerImpl scannerReadPoints synchronization costs
> -----------------------------------------------------------------
>
> Key: HBASE-15716
> URL: https://issues.apache.org/jira/browse/HBASE-15716
> Project: HBase
> Issue Type: Bug
> Components: Performance
> Reporter: stack
> Attachments: 15716.prune.synchronizations.patch,
> 15716.prune.synchronizations.v3.patch, Screen Shot 2016-04-26 at 2.05.45
> PM.png, Screen Shot 2016-04-26 at 2.06.14 PM.png, Screen Shot 2016-04-26 at
> 2.07.06 PM.png, Screen Shot 2016-04-26 at 2.25.26 PM.png, Screen Shot
> 2016-04-26 at 6.02.29 PM.png, Screen Shot 2016-04-27 at 9.49.35 AM.png,
> hits.png, remove_cslm.patch
>
>
> Here is a [~lhofhansl] special.
> When we construct the region scanner, we get our read point and then store it
> with the scanner instance in a Region scoped CSLM. This is done under a
> synchronize on the CSLM.
> This synchronize on a region-scoped Map creating region scanners is the
> outstanding point of lock contention according to flight recorder (My work
> load is workload c, random reads).
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