[jira] [Updated] (HBASE-20921) Possible NPE in ReopenTableRegionsProcedure

["Allan Yang (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-20921?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Allan Yang updated HBASE-20921:
-------------------------------
    Status: Patch Available  (was: Open)

> 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
>            Priority: Major
>
> 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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