[jira] [Resolved] (HBASE-21051) Possible NPE if ModifyTable and region split happen at the same time

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

     [ https://issues.apache.org/jira/browse/HBASE-21051?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack resolved HBASE-21051.
---------------------------
    Resolution: Duplicate

Resolving as duplicate of HBASE-21078.  I thought them 'similar' but they are the same. HBASE-21078 implements the idea suggested on the tail of this issue by [~allan163].  Added to the parent issue the suggestion by [~Apache9] that we need to be able to have a Procedure selectively hold locks across their lifetime -- a PE modification.

> Possible NPE if ModifyTable and region split happen at the same time
> --------------------------------------------------------------------
>
>                 Key: HBASE-21051
>                 URL: https://issues.apache.org/jira/browse/HBASE-21051
>             Project: HBase
>          Issue Type: Sub-task
>          Components: amv2
>    Affects Versions: 2.1.0, 2.0.1
>            Reporter: Allan Yang
>            Assignee: Allan Yang
>            Priority: Major
>
> Similar with HBASE-20921, ModifyTable procedure and reopenProcedure won't held the lock, so another procedures like split/merge can execute at the same time.
> 1. a split happend during ModifyTable, as you can see from the log, the split was nealy complete.
> {code}
> 2018-08-05 01:28:31,339 INFO  [PEWorker-8] procedure2.ProcedureExecutor(1659): Finished subprocedure(s) of pid=772, state=RUNNABLE:SPLIT_TABLE_REGION_POST_OPERATION, hasLock=true; SplitTableRegionProce
> dure table=IntegrationTestBigLinkedList, parent=357a7a6a62c76bc2d7ab30a6cc812637, daughterA=b13e5d155b65a5f752f3adda78fcfb6a, daughterB=5be3aadcee68d91c3d1e464865550246; resume parent processing.
> 2018-08-05 01:28:31,345 INFO  [PEWorker-8] procedure2.ProcedureExecutor(1296): Finished pid=795, ppid=772, state=SUCCESS, hasLock=false; AssignProcedure table=IntegrationTestBigLinkedList, region=b13e5
> d155b65a5f752f3adda78fcfb6a, target=e010125048016.bja,60020,1533402809226 in 5.0280sec
> {code}
> 2. reopenProcedure began to reopen region by moving it
> {code}
> 2018-08-05 01:28:31,389 INFO  [PEWorker-11] procedure.MasterProcedureScheduler(631): pid=781, ppid=774, state=RUNNABLE:MOVE_REGION_UNASSIGN, hasLock=false; MoveRegionProcedure hri=357a7a6a62c76bc2d7ab3
> 0a6cc812637, source=e010125048016.bja,60020,1533402809226, destination=e010125048016.bja,60020,1533402809226 checking lock on 357a7a6a62c76bc2d7ab30a6cc812637
> 2018-08-05 01:28:31,390 INFO  [PEWorker-3] procedure2.ProcedureExecutor(1296): Finished pid=772, state=SUCCESS, hasLock=false; SplitTableRegionProcedure table=IntegrationTestBigLinkedList, parent=357a7
> a6a62c76bc2d7ab30a6cc812637, daughterA=b13e5d155b65a5f752f3adda78fcfb6a, daughterB=5be3aadcee68d91c3d1e464865550246 in 21.9050sec
> 2018-08-05 01:28:31,518 INFO  [PEWorker-11] procedure2.ProcedureExecutor(1533): Initialized subprocedures=[{pid=797, ppid=781, state=RUNNABLE:REGION_TRANSITION_DISPATCH, hasLock=false; UnassignProcedur
> e table=IntegrationTestBigLinkedList, region=357a7a6a62c76bc2d7ab30a6cc812637, server=e010125048016.bja,60020,1533402809226}]
> 2018-08-05 01:28:31,530 INFO  [PEWorker-15] procedure.MasterProcedureScheduler(631): pid=797, ppid=781, state=RUNNABLE:REGION_TRANSITION_DISPATCH, hasLock=false; UnassignProcedure table=IntegrationTest
> BigLinkedList, region=357a7a6a62c76bc2d7ab30a6cc812637, server=e010125048016.bja,60020,1533402809226 checking lock on 357a7a6a62c76bc2d7ab30a6cc812637
> {code}
> 3. MoveRegionProcdure fails since the region did not exis any more (due to split)
> {code}
> 2018-08-05 01:28:31,543 ERROR [PEWorker-15] procedure2.ProcedureExecutor(1517): CODE-BUG: Uncaught runtime exception: pid=797, ppid=781, state=RUNNABLE:REGION_TRANSITION_DISPATCH, hasLock=true; Unassig
> nProcedure table=IntegrationTestBigLinkedList, region=357a7a6a62c76bc2d7ab30a6cc812637, server=e010125048016.bja,60020,1533402809226
> java.lang.NullPointerException
>         at java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:936)
>         at org.apache.hadoop.hbase.master.assignment.RegionStates.getOrCreateServer(RegionStates.java:1097)
>         at org.apache.hadoop.hbase.master.assignment.RegionStates.addRegionToServer(RegionStates.java:1125)
>         at org.apache.hadoop.hbase.master.assignment.AssignmentManager.markRegionAsClosing(AssignmentManager.java:1455)
>         at org.apache.hadoop.hbase.master.assignment.UnassignProcedure.updateTransition(UnassignProcedure.java:204)
>         at org.apache.hadoop.hbase.master.assignment.RegionTransitionProcedure.execute(RegionTransitionProcedure.java:349)
>         at org.apache.hadoop.hbase.master.assignment.RegionTransitionProcedure.execute(RegionTransitionProcedure.java:101)
>         at org.apache.hadoop.hbase.procedure2.Procedure.doExecute(Procedure.java:873)
>         at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execProcedure(ProcedureExecutor.java:1498)
>         at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeProcedure(ProcedureExecutor.java:1278)
>         at org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$900(ProcedureExecutor.java:76)
>         at org.apache.hadoop.hbase.procedure2.ProcedureExecutor$WorkerThread.run(ProcedureExecutor.java:1785)
> {code}
> We need to think about the case, and find a ultimately solution for it, otherwise, issues like this one and HBASE-20921 will keep comming.



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