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https://issues.apache.org/jira/browse/HBASE-28405?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17834626#comment-17834626
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Duo Zhang commented on HBASE-28405:
-----------------------------------
The root cause here is we should not issue a TRSP to bring the region online if
the region is not closed.
I could provide a PR to show how to fix this problem.
There are other pending problems, like whether we should always ignore the
redundant open request at rs side, how to deal with MERGING state in
checkOnlineRegions, is it the correct way to set region to SPLITTING/MERGING
before making it offline. We can file other issues for these problems.
Thanks.
> Region open procedure silently returns without notifying the parent proc
> ------------------------------------------------------------------------
>
> Key: HBASE-28405
> URL: https://issues.apache.org/jira/browse/HBASE-28405
> Project: HBase
> Issue Type: Bug
> Components: proc-v2
> Affects Versions: 2.5.7
> Reporter: Aman Poonia
> Assignee: Aman Poonia
> Priority: Major
>
> *We had a scenario in production where a merge operation had failed as below*
> _2024-02-11 10:53:57,715 ERROR [PEWorker-31]
> assignment.MergeTableRegionsProcedure - Error trying to merge
> [a92008b76ccae47d55c590930b837036, f56752ae9f30fad9de5a80a8ba578e4b] in
> table1 (in state=MERGE_TABLE_REGIONS_CLOSE_REGIONS)_
> _org.apache.hadoop.hbase.HBaseIOException: The parent region state=MERGING,
> location=rs-229,60020,1707587658182, table=table1,
> region=f56752ae9f30fad9de5a80a8ba578e4b is currently in transition, give up_
> _at
> org.apache.hadoop.hbase.master.assignment.AssignmentManagerUtil.createUnassignProceduresForSplitOrMerge(AssignmentManagerUtil.java:120)_
> _at
> org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure.createUnassignProcedures(MergeTableRegionsProcedure.java:648)_
> _at
> org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure.executeFromState(MergeTableRegionsProcedure.java:205)_
> _at
> org.apache.hadoop.hbase.master.assignment.MergeTableRegionsProcedure.executeFromState(MergeTableRegionsProcedure.java:79)_
> _at
> org.apache.hadoop.hbase.procedure2.StateMachineProcedure.execute(StateMachineProcedure.java:188)_
> _at
> org.apache.hadoop.hbase.procedure2.Procedure.doExecute(Procedure.java:922)_
> _at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.execProcedure(ProcedureExecutor.java:1650)_
> _at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.executeProcedure(ProcedureExecutor.java:1396)_
> _at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor.access$1000(ProcedureExecutor.java:75)_
> _at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor$WorkerThread.runProcedure(ProcedureExecutor.java:1964)_
> _at org.apache.hadoop.hbase.trace.TraceUtil.trace(TraceUtil.java:216)_
> _at
> org.apache.hadoop.hbase.procedure2.ProcedureExecutor$WorkerThread.run(ProcedureExecutor.java:1991)_
> *Now when we do rollback of failed merge operation we see a issue where
> region is in state opened until the RS holding it stopped.*
> Rollback create a TRSP as below
> _2024-02-11 10:53:57,719 DEBUG [PEWorker-31] procedure2.ProcedureExecutor -
> Stored [pid=26674602,
> state=RUNNABLE:REGION_STATE_TRANSITION_GET_ASSIGN_CANDIDATE;
> TransitRegionStateProcedure table=table1,
> region=a92008b76ccae47d55c590930b837036, ASSIGN]_
> *and rollback finished successfully*
> _2024-02-11 10:53:57,721 INFO [PEWorker-31] procedure2.ProcedureExecutor -
> Rolled back pid=26673594, state=ROLLEDBACK,
> exception=org.apache.hadoop.hbase.HBaseIOException via
> master-merge-regions:org.apache.hadoop.hbase.HBaseIOException: The parent
> region state=MERGING, location=rs-229,60020,1707587658182, table=table1,
> region=f56752ae9f30fad9de5a80a8ba578e4b is currently in transition, give up;
> MergeTableRegionsProcedure table=table1,
> regions=[a92008b76ccae47d55c590930b837036, f56752ae9f30fad9de5a80a8ba578e4b],
> force=false exec-time=1.4820 sec_
> *We create a procedure to open the region a92008b76ccae47d55c590930b837036.
> Intrestingly we didnt close the region as creation of procedure to close
> regions had thrown exception and not execution of procedure. When we run TRSP
> it sends a OpenRegionProcedure which is handled by AssignRegionHandler. This
> handlers on execution suggests that region is already online*
> Sequence of events are as follow
> _2024-02-11 10:53:58,919 INFO [PEWorker-58] assignment.RegionStateStore -
> pid=26674602 updating hbase:meta row=a92008b76ccae47d55c590930b837036,
> regionState=OPENING, regionLocation=rs-210,60020,1707596461539_
> _2024-02-11 10:53:58,920 INFO [PEWorker-58] procedure2.ProcedureExecutor -
> Initialized subprocedures=[\\{pid=26675798, ppid=26674602, state=RUNNABLE;
> OpenRegionProcedure a92008b76ccae47d55c590930b837036,
> server=rs-210,60020,1707596461539}]_
> _2024-02-11 10:53:59,074 WARN [REGION-regionserver/rs-210:60020-10]
> handler.AssignRegionHandler - Received OPEN for
> table1,r1,1685436252488.a92008b76ccae47d55c590930b837036. which is already
> online_
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