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https://issues.apache.org/jira/browse/HBASE-15716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15357020#comment-15357020
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stack commented on HBASE-15716:
-------------------------------
This sounds interesting [~ikeda]. Let me see if I understand properly so I can
try it. What goes in the registrationQueue? I'd add the just-accepted channel?
Are you saying Selector.select in the Listener or readSelector.select in the
Reader? When the latter is called, I'd register anything in the registerQueue?
Any opinions on whether it makes more sense to have one Selector only rather
than as we have now? I was going to try it. Thanks [~ikeda]
> 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.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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