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https://issues.apache.org/jira/browse/HBASE-10117?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Lars Hofhansl updated HBASE-10117:
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Attachment: 10117-0.94.txt
0.94 patch.
Speeds up a Phoenix count(1) query on a tall table by 20-25%.
> Avoid synchronization in HRegionScannerImpl.isFilterDone
> --------------------------------------------------------
>
> Key: HBASE-10117
> URL: https://issues.apache.org/jira/browse/HBASE-10117
> Project: HBase
> Issue Type: Bug
> Components: Performance
> Reporter: Lars Hofhansl
> Fix For: 0.94.15, 0.96.2, 0.98.1
>
> Attachments: 10117-0.94.txt
>
>
> A while ago I introduced HRegoinScannerImpl.nextRaw() to allow coprocessors
> and scanners with caching > 1 to avoid repeated synchronization during the
> scanning (which puts up memory fences, which in turns slows things down on
> multi core machines).
> Looking at the code again I see that isFilterDone() is called from nextRaw()
> and isFilterDone() is synchronized. isFilterDone() is only called from two
> places. The other place is rare in RegionServer.next() when we're bypassing
> at the request of a coprocessor. We can add synchronization there.
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