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From "Sergey Shelukhin (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-21614) RIT recovery with ServerCrashProcedure is broken in multiple ways
Date Tue, 18 Dec 2018 22:12:00 GMT
Sergey Shelukhin created HBASE-21614:
----------------------------------------

             Summary: RIT recovery with ServerCrashProcedure is broken in multiple ways
                 Key: HBASE-21614
                 URL: https://issues.apache.org/jira/browse/HBASE-21614
             Project: HBase
          Issue Type: Bug
            Reporter: Sergey Shelukhin


Master is restarting after a previous master crashed while recovering some regions from a
dead server.

Master recovers RIT for the region, however the RIT has no location (logged, at least) in
CONFIRM_CLOSE state. That is a potential problem #1 - confirm where? But that should be covered
by meta, so not a big deal, right.
{noformat}
2018-12-17 14:51:14,606 INFO  [master/:17000:becomeActiveMaster] assignment.AssignmentManager:
Attach pid=38015, state=RUNNABLE:REGION_STATE_TRANSITION_CONFIRM_CLOSED, hasLock=false; TransitRegionStateProcedure
table=t1, region=region1, REOPEN/MOVE to rit=OFFLINE, location=null, table=t1, region=region1
to restore RIT
{noformat}

However, in this case ServerCrashProcedure for the server kicks off BEFORE meta is loaded.
That seems to be a problem #2 - it immediately gets regions to later recover, so in this case
it gets nothing.
I've grepped our logs for successful cases of SCP interacting with TRANSITION_CONFIRM_CLOSED,
and in all cases the meta was loaded before SCP.
Seems like a race condition.
{noformat}
2018-12-17 14:51:14,625 INFO  [master/:17000:becomeActiveMaster] master.RegionServerTracker:
Starting RegionServerTracker; 0 have existing ServerCrashProcedures, 103 possibly 'live' servers,
and 1 'splitting'.
2018-12-17 14:51:20,770 INFO  [master/:17000:becomeActiveMaster] master.ServerManager: Processing
expiration of server1,17020,1544636616174 on ,17000,1545087053243
2018-12-17 14:51:20,921 INFO  [master/:17000:becomeActiveMaster] assignment.AssignmentManager:
Added server1,17020,1544636616174 to dead servers which carryingMeta=false, submitted ServerCrashProcedure
pid=111298
2018-12-17 14:51:30,728 INFO  [PEWorker-13] procedure.ServerCrashProcedure: Start pid=111298,
state=RUNNABLE:SERVER_CRASH_START, hasLock=true; ServerCrashProcedure server=server1,17020,1544636616174,
splitWal=true, meta=false
{noformat}
Meta is only loaded 11-12 seconds later.
If one looks at meta-loading code however, there is one more problem - the region is in CLOSING
state, so the {{addRegionToServer}} is not going to be called - it's only called for OPENED
regions. 
Expanding on the above, I've only seen SCP unblock stuck TRANSITION_CONFIRM_CLOSED when region
started out in meta as OPEN.
{noformat}
2018-12-17 14:51:42,403 INFO  [master/:17000:becomeActiveMaster] assignment.RegionStateStore:
Load hbase:meta entry region=region1, regionState=CLOSING, lastHost=server1,17020,1544636616174,
regionLocation=server1,17020,1544636616174, openSeqNum=629131
{noformat}
SCP predictably finishes without doing anything; no other logs for this pid
{noformat}
2018-12-17 14:52:19,046 INFO  [PEWorker-2] procedure2.ProcedureExecutor: Finished pid=111298,
state=SUCCESS, hasLock=false; ServerCrashProcedure server=server1,17020,1544636616174, splitWal=true,
meta=false in 58.0010sec
{noformat}
After that, region is still stuck trying to be closed in TransitRegionStateProcedure; it's
in the same state for hours including across master restarts.
{noformat}
2018-12-17 15:09:35,216 WARN  [PEWorker-14] assignment.TransitRegionStateProcedure: Failed
transition, suspend 604secs pid=38015, state=RUNNABLE:REGION_STATE_TRANSITION_CLOSE, hasLock=true;
TransitRegionStateProcedure table=t1, region=region1, REOPEN/MOVE; rit=CLOSING, location=server1,17020,1544636616174;
waiting on rectified condition fixed by other Procedure or operator intervention
{noformat}





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