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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:
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Attachment: (was: Screenshot from 2020-11-24 15-23-29.png)
> 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
> Fix For: 3.0.0-alpha-1
>
> Attachments: Screenshot from 2020-11-24 15-23-29.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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