Allan Yang created HBASE-21051:
----------------------------------
Summary: 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: 2.0.1, 2.1.0
Reporter: Allan Yang
Assignee: Allan Yang
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 untimely solution for it,
otherwise, issues like this one and HBASE-20921 will keep comming.
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