Allan Yang created HBASE-20921:
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Summary: Possible NPE in ReopenTableRegionsProcedure
Key: HBASE-20921
URL: https://issues.apache.org/jira/browse/HBASE-20921
Project: HBase
Issue Type: Sub-task
Components: amv2
Affects Versions: 2.1.0, 3.0.0, 2.0.2
Reporter: Allan Yang
Assignee: Allan Yang
After HBASE-20752， we issue a ReopenTableRegionsProcedure in
ModifyTableProcedure to ensure all regions are reopened.
But, ModifyTableProcedure and ReopenTableRegionsProcedure do not hold the lock
(why?), so there is a chance that while ModifyTableProcedure executing, a
merge/split procedure can be executed at the same time.
So, when ReopenTableRegionsProcedure reaches the state of
"REOPEN_TABLE_REGIONS_CONFIRM_REOPENED", some of the persisted regions to check
is actually not exists, thus a NPE will throw.
{code}
2018-07-18 01:38:57,528 INFO [PEWorker-9] procedure2.ProcedureExecutor(1246):
Finished pid=6110, state=SUCCESS; MergeTableRegionsProcedure
table=IntegrationTestBigLinkedList, regions=[845d286231eb01b7
1aeaa17b0e30058d, 4a46ab0918c99cada72d5336ad83a828], forcibly=false in
10.8610sec
2018-07-18 01:38:57,530 ERROR [PEWorker-8] procedure2.ProcedureExecutor(1478):
CODE-BUG: Uncaught runtime exception: pid=5974, ppid=5973,
state=RUNNABLE:REOPEN_TABLE_REGIONS_CONFIRM_REOPENED; ReopenTab
leRegionsProcedure table=IntegrationTestBigLinkedList
java.lang.NullPointerException
at
org.apache.hadoop.hbase.master.assignment.RegionStates.checkReopened(RegionStates.java:651)
at
java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
at
java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at
java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at
java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at
java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
at
org.apache.hadoop.hbase.master.procedure.ReopenTableRegionsProcedure.executeFromState(ReopenTableRegionsProcedure.java:102)
at
org.apache.hadoop.hbase.master.procedure.ReopenTableRegionsProcedure.executeFromState(ReopenTableRegionsProcedure.java:45)
at
org.apache.hadoop.hbase.procedure2.StateMachineProcedure.execute(StateMachineProcedure.java:184)
at
org.apache.hadoop.hbase.procedure2.Procedure.doExecute(Procedure.java:850)
at
org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execProcedure(ProcedureExecutor.java:1453)
at
org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeProcedure(ProcedureExecutor.java:1221)
at
org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$800(ProcedureExecutor.java:75)
at
org.apache.hadoop.hbase.procedure2.ProcedureExecutor$WorkerThread.run(ProcedureExecutor.java:1741)
{code}
I think we need to renew the region list of the table at the
"REOPEN_TABLE_REGIONS_CONFIRM_REOPENED" state. For the regions which are merged
or split, we do not need to check it. Since we can make sure that they are
opened after we made change to table descriptor.
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