Pankaj Kumar created HBASE-25277:
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Summary: 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
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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