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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10117) Avoid synchronization in HRegionScannerImpl.isFilterDone
Date Tue, 10 Dec 2013 16:40:07 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10117?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13844405#comment-13844405
] 

stack commented on HBASE-10117:
-------------------------------

+1 on change.

> 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
>            Assignee: Lars Hofhansl
>             Fix For: 0.94.15, 0.96.2, 0.98.1, 0.99.0
>
>         Attachments: 10117-0.94-v2.txt, 10117-0.94-v3.txt, 10117-0.94.txt, 10117-trunk-v2.txt,
10117-trunk.txt
>
>
> A while ago I introduced HRegoinScannerImpl.nextRaw() to allow coprocessors and scanners
with caching > 1 to avoid repeated synchronization during scanning (which puts up memory
fences, which in turn slows things down on multi core machines).
> Looking at the code again I see that isFilterDone() is called from nextRaw() and isFilterDone()
is synchronized.
> The caller of nextRaw is required to ensure single threaded access to nextRaw() anyway,
we can call an unsynchronized internal version of isFilterDone().



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