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https://issues.apache.org/jira/browse/HBASE-25277?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pankaj Kumar updated HBASE-25277:
---------------------------------
    Resolution: Fixed
        Status: Resolved  (was: Patch Available)

Pushed to branch-2.3+ branch. Couldn't merge in branch-2.2 because QA is not 
running due to docker failure.

 [~zghao], please help me to resolved the build problem in  
[https://github.com/apache/hbase/pull/2765] . Resolving this Jira for now.

> postScannerFilterRow impacts Scan performance a lot in HBase 2.x
> ----------------------------------------------------------------
>
>                 Key: HBASE-25277
>                 URL: https://issues.apache.org/jira/browse/HBASE-25277
>             Project: HBase
>          Issue Type: Bug
>          Components: Coprocessors, scan
>            Reporter: Pankaj Kumar
>            Assignee: Pankaj Kumar
>            Priority: Critical
>              Labels: perfomance, scanning
>             Fix For: 3.0.0-alpha-1, 2.3.4, 2.5.0, 2.4.0
>
>         Attachments: test_report.png
>
>
> In our test we observed Scan performance is degraded by more than 60% in 
> HBase-2.x as compared to 1.3.x.  As per the flamegraph report, RS spent 31% 
> of the time in postScannerFilterRow, however the coprocessors 
> (AccessController, VisibilityController & ConstraintProcessor) does nothing 
> in that hook.
> HBASE-14489 added the logic to avoid the call to postScannerFilterRow when 
> not needed which is not working as expected in HBase 2.x. AccessController, 
> VisibilityController & ConstraintProcessor override the postScannerFilterRow 
> with dummy (same as RegionObserver) implementation, so 
> RegionCoprocessorHost.hasCustomPostScannerFilterRow will be TRUE and call the 
> hook for all configured CPs while processing each row .  Suppose we have 
> configured 5 region CPs and there are 1 M rows in table, then there will be 1 
> * 5 M dummy call to postScannerFilterRow during whole table scan.
> We need to remove postScannerFilterRow hook from these CPs as these are not 
> doing anything.
> Another problem is in RegionCoprocessorHost.hasCustomPostScannerFilterRow 
> init logic, currently it is always TRUE even though we remove 
> postScannerFilterRow hook from AccessController, VisibilityController & 
> ConstraintProcessor, because we are finding  postScannerFilterRow until  it 
> is found (we look in configured CP's super class also) or clazz is NULL.
> https://github.com/apache/hbase/blob/035c192eb665469ce0c071db86c78f4a873c123b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java#L301
> Supper class of Object (super class of AccessController) will be NULL, so 
> RegionCoprocessorHost.hasCustomPostScannerFilterRow will be set as TRUE
> https://github.com/apache/hbase/blob/035c192eb665469ce0c071db86c78f4a873c123b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java#L279



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