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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: remove.locks.patch
Patch w/ alternate implementation for registering region scanners (for
consideration -- two volatile reads in place of synchronization blocks...) and
that removes unnecessary locks. Changes nature of the thread dumps so we are
now just blocking reading and writing on channels (for most part -- some work
to be done still). Doesn't get us much... maybe 5-10% on throughput. Let me
see...
> 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,
> 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,
> 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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