[HBASE-13061] RegionStates can remove wrong region from server holdings

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.0, 2.0.0
• Fix Version/s: 1.0.1, 1.1.0, 2.0.0
• Component/s: Region Assignment
• Hadoop Flags: Reviewed
• Assignee: Andrey Stepachev
• Reporter: Andrey Stepachev
• Created: 18/Feb/15 01:49
• Updated: 28/Apr/15 19:18
• Resolved: 18/Feb/15 14:26

Description

Got failed test in HBASE-13017. It seems that with zk nodes were ordered in one way and test didn't trigger error, but with new meta rows ordered differently test became flakey.

That leads to interesting sequence of offline/online regions and triggers bug and NPE in AM (thats seen in TestZKLessAMOnCluster)

That can happen if region was moved from RS1 to other region server RS2, and thats happens that RS2 failed. Region remains in PENDING_OPEN. SSH will offline it from RS1(without removing from oldAssignments because of disabled table). When AssingnmentManager come and assign region it then removes oldAssignment of region from serverHoldings. And thats happen to be our just assigned RS1.

Small bit of logs. Most interesting are last 3 lines, region b73fe9f1185361e846b0e1ceb7d6d64e added to server and immediately removed from it. Later that triggers NPE in disable table handler.

2015-02-18 01:21:18,338 INFO  [Thread-436] master.RegionStates(1109): Transition {b73fe9f1185361e846b0e1ceb7d6d64e state=PENDING_OPEN, ts=1424222478324, server=octobook.home,65370,1424222474885} to {b73fe9f1185361e846b0e1ceb7d6d64e state=OFFLINE, ts=1424222478338, server=octobook.home,65370,1424222474885}
2015-02-18 01:21:18,339 INFO  [Thread-436] master.RegionStateStore(218): Updating row testSSHWhenDisablingTableRegionsInOpeningOrPendingOpenState,I,1424222477651.b73fe9f1185361e846b0e1ceb7d6d64e. with state=OFFLINE
2015-02-18 01:21:18,340 DEBUG [Thread-436] master.RegionStates(591): Old server name for {ENCODED => b73fe9f1185361e846b0e1ceb7d6d64e, NAME => 'testSSHWhenDisablingTableRegionsInOpeningOrPendingOpenState,I,1424222477651.b73fe9f1185361e846b0e1ceb7d6d64e.', STARTKEY => 'I', ENDKEY => 'Q'} is null
2015-02-18 01:21:18,340 INFO  [Thread-436] master.RegionStates(1109): Transition {b73fe9f1185361e846b0e1ceb7d6d64e state=OFFLINE, ts=1424222478338, server=octobook.home,65370,1424222474885} to {b73fe9f1185361e846b0e1ceb7d6d64e state=OPEN, ts=1424222478340, server=octobook.home,65359,1424222474743}
2015-02-18 01:21:18,341 INFO  [Thread-436] master.RegionStateStore(218): Updating row testSSHWhenDisablingTableRegionsInOpeningOrPendingOpenState,I,1424222477651.b73fe9f1185361e846b0e1ceb7d6d64e. with state=OPEN&sn=octobook.home,65359,1424222474743
2015-02-18 01:21:18,342 DEBUG [Thread-436] master.RegionStates(457): Onlined b73fe9f1185361e846b0e1ceb7d6d64e on octobook.home,65359,1424222474743 {ENCODED => b73fe9f1185361e846b0e1ceb7d6d64e, NAME => 'testSSHWhenDisablingTableRegionsInOpeningOrPendingOpenState,I,1424222477651.b73fe9f1185361e846b0e1ceb7d6d64e.', STARTKEY => 'I', ENDKEY => 'Q'}
2015-02-18 01:21:18,342 DEBUG [Thread-436] master.RegionStates(481): Adding  b73fe9f1185361e846b0e1ceb7d6d64e to server octobook.home,65359,1424222474743
2015-02-18 01:21:18,342 INFO  [Thread-436] master.RegionStates(467): Offlined b73fe9f1185361e846b0e1ceb7d6d64e from octobook.home,65359,1424222474743
2015-02-18 01:21:18,342 DEBUG [Thread-436] master.RegionStates(496): Removing b73fe9f1185361e846b0e1ceb7d6d64e from server octobook.home,65359,1424222474743