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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15716) HRegion#RegionScannerImpl scannerReadPoints synchronization costs
Date Wed, 27 Apr 2016 17:34:13 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15716?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15260556#comment-15260556
] 

stack commented on HBASE-15716:
-------------------------------

It think the patches before v3 have a hole. v3 looks better to me [~lhofhansl]

[~ikeda] You have an opinion sir?

> 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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