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https://issues.apache.org/jira/browse/HBASE-15716?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack updated HBASE-15716:
--------------------------
Attachment: 15716.implementation.using.ScannerReadPoints.branch-1.patch
Patch that uses [~ikeda] suggestion. Testing it now.
[~ikeda] Implementation is nice. I don't see any holes (getSmallestReadPoint
marches from head to tail and then if nothing, gets mvcc read point...
Meantime, we are adding entries on the tail... and only creating an Entry if
successful add or we were able to update ref count..)
> HRegion#RegionScannerImpl scannerReadPoints synchronization constrains random
> read
> ----------------------------------------------------------------------------------
>
> Key: HBASE-15716
> URL: https://issues.apache.org/jira/browse/HBASE-15716
> Project: HBase
> Issue Type: Bug
> Components: Performance
> Reporter: stack
> Assignee: stack
> Attachments:
> 15716.implementation.using.ScannerReadPoints.branch-1.patch,
> 15716.prune.synchronizations.patch, 15716.prune.synchronizations.v3.patch,
> 15716.prune.synchronizations.v4.patch, 15716.prune.synchronizations.v4.patch,
> 15716.wip.more_to_be_done.patch, HBASE-15716.branch-1.001.patch,
> HBASE-15716.branch-1.002.patch, HBASE-15716.branch-1.003.patch,
> HBASE-15716.branch-1.004.patch, ScannerReadPoints.java, 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, TestScannerReadPoints.java, before_after.png,
> current-branch-1.vs.NoSynchronization.vs.Patch.png, hits.png,
> remove.locks.patch, 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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