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https://issues.apache.org/jira/browse/HBASE-11217?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14006683#comment-14006683
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Enis Soztutar commented on HBASE-11217:
---------------------------------------
hadoopqa is still not updated with git repo AFAIK. I've run the tests locally.
Committed the addendum to master and 0.98.
> Race between SplitLogManager task creation + TimeoutMonitor
> -----------------------------------------------------------
>
> Key: HBASE-11217
> URL: https://issues.apache.org/jira/browse/HBASE-11217
> Project: HBase
> Issue Type: Bug
> Reporter: Enis Soztutar
> Assignee: Enis Soztutar
> Priority: Critical
> Fix For: 0.99.0, 0.98.3
>
> Attachments: hbase-11217_addendum.patch, hbase-11217_v1.patch,
> hbase-11217_v2.patch
>
>
> Some time ago, we reported a test failure in HBASE-11036, which resulted in
> already-split and merged regions coming back to life, causing split brain for
> region boundaries and resulting in data loss.
> It turns out that the root cause was not concurrent online schema change +
> region split/merge, but meta log splitting failing and the meta updates
> getting lost. This in turn causes the region split/merge information and
> assignment to be lost causing large scale data loss.
> Logs below shows that the split task for meta log is created, but before the
> znode is created, the timeout thread kicks in and sees the unassigned task.
> Then it does a get on znode which fails with NoNode (because the znode is not
> created yet). This causes the task to be marked complete (setDone(path,
> SUCCESS)) which means that the logs are lost. Meta is assigned elsewhere (and
> opened with the same seqId as previous) confirming data loss in meta.
> {code}
> 2014-04-16 18:31:26,267 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2]
> handler.MetaServerShutdownHandler: Splitting hbase:meta logs for
> hor13n03.gq1.ygridcore.net,60020,1397672668647
> 2014-04-16 18:31:26,274 DEBUG
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.MasterFileSystem:
> Renamed region directory:
> hdfs://hor13n01.gq1.ygridcore.net:8020/apps/hbase/data/WALs/hor13n03.gq1.ygridcore.net,60020,1397672668647-splitting
> 2014-04-16 18:31:26,274 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.SplitLogManager: dead
> splitlog workers [hor13n03.gq1.ygridcore.net,60020,1397672668647]
> 2014-04-16 18:31:26,276 DEBUG
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.SplitLogManager:
> Scheduling batch of logs to split
> 2014-04-16 18:31:26,276 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.SplitLogManager:
> started splitting 1 logs in
> [hdfs://hor13n01.gq1.ygridcore.net:8020/apps/hbase/data/WALs/hor13n03.gq1.ygridcore.net,60020,1397672668647-splitting]
> 2014-04-16 18:31:26,276 INFO
> [hor13n02.gq1.ygridcore.net,60000,1397672191204.splitLogManagerTimeoutMonitor]
> master.SplitLogManager: total tasks = 1 unassigned = 1
> tasks={/hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta=last_update
> = -1 last_version = -
> 2014-04-16 18:31:26,276 DEBUG
> [hor13n02.gq1.ygridcore.net,60000,1397672191204.splitLogManagerTimeoutMonitor]
> master.SplitLogManager: resubmitting unassigned task(s) after timeout
> 2014-04-16 18:31:26,277 WARN [main-EventThread]
> master.SplitLogManager$GetDataAsyncCallback: task znode
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> vanished.
> 2014-04-16 18:31:26,277 INFO [main-EventThread] master.SplitLogManager: Done
> splitting
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> 2014-04-16 18:31:26,282 DEBUG [main-EventThread] master.SplitLogManager: put
> up splitlog task at znode
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
>
>
> 2014-04-16 18:31:26,286 WARN
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.SplitLogManager:
> returning success without actually splitting and deleting all the log files
> in path
> hdfs://hor13n01.gq1.ygridcore.net:8020/apps/hbase/data/WALs/hor13n03.gq1.ygridcore.net,60020,1397672668647-splitting
> 2014-04-16 18:31:26,286 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.SplitLogManager:
> finished splitting (more than or equal to) 9 bytes in 1 log files in
> [hdfs://hor13n01.gq1.ygridcore.net:8020/apps/hbase/data/WALs/hor13n03.gq1.ygridcore.net,60020,1397672668647-splitting]
> in 10ms
> 2014-04-16 18:31:26,290 DEBUG [main-EventThread]
> master.SplitLogManager$DeleteAsyncCallback: deleted
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> 2014-04-16 18:31:26,290 WARN [main-EventThread]
> master.SplitLogManager$GetDataAsyncCallback: task znode
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> vanished.
> 2014-04-16 18:31:26,290 DEBUG [main-EventThread] master.SplitLogManager:
> unacquired orphan task is done
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> 2014-04-16 18:31:26,291 INFO [main-EventThread] master.SplitLogManager: task
> /hbase/splitWAL/RESCAN0000000383 entered state: DONE
> hor13n02.gq1.ygridcore.net,60000,1397672191204
> 2014-04-16 18:31:26,291 DEBUG
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.AssignmentManager:
> based on AM, current region=hbase:meta,,1.1588230740 is on
> server=hor13n03.gq1.ygridcore.net,60020,1397672668647 server being checked:
> hor13n03.gq1.ygridcore.net,60020,1397672668647
> 2014-04-16 18:31:26,291 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2]
> handler.MetaServerShutdownHandler: Server
> hor13n03.gq1.ygridcore.net,60020,1397672668647 was carrying META. Trying to
> assign.
> 2014-04-16 18:31:26,291 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.RegionStates:
> Transitioned {1588230740 state=OPEN, ts=1397672681933,
> server=hor13n03.gq1.ygridcore.net,60020,1397672668647} to {1588230740
> state=OFFLINE, ts=1397673086291,
> server=hor13n03.gq1.ygridcore.net,60020,1397672668647}
> 2014-04-16 18:31:26,291 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.RegionStates:
> Offlined 1588230740 from hor13n03.gq1.ygridcore.net,60020,1397672668647
> 2014-04-16 18:31:26,299 INFO [main-EventThread]
> master.SplitLogManager$DeleteAsyncCallback:
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> does not exist. Either was created but deleted behind our back by another
> pending delete OR was deleted in earl
> 2014-04-16 18:31:26,299 DEBUG [main-EventThread] master.SplitLogManager:
> deleted task without in memory state
> /hbase/splitWAL/WALs%2Fhor13n03.gq1.ygridcore.net%2C60020%2C1397672668647-splitting%2Fhor13n03.gq1.ygridcore.net%252C60020%252C1397672668647.1397672681632.meta
> 2014-04-16 18:31:26,299 DEBUG [main-EventThread]
> master.SplitLogManager$DeleteAsyncCallback: deleted
> /hbase/splitWAL/RESCAN0000000383
> 2014-04-16 18:31:26,299 DEBUG [main-EventThread] master.SplitLogManager:
> deleted task without in memory state /hbase/splitWAL/RESCAN0000000383
> 2014-04-16 18:31:26,301 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] catalog.CatalogTracker:
> Failed verification of hbase:meta,,1 at
> address=hor13n03.gq1.ygridcore.net,60020,1397672668647,
> exception=java.net.ConnectException: Connection refused
> 2014-04-16 18:31:26,301 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2]
> zookeeper.ZooKeeperNodeTracker: Unsetting hbase:meta region location in
> ZooKeeper
> 2014-04-16 18:31:26,315 DEBUG
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.AssignmentManager: No
> previous transition plan found (or ignoring an existing plan) for
> hbase:meta,,1.1588230740; generated random plan=hri=hbase:meta,,1.1588230740,
> src=, dest=hor13n04.gq1.ygridcore.net,60020,1397672685370; 3 (online=3,
> available=3) available servers, forceNew
> 2014-04-16 18:31:26,315 DEBUG
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] zookeeper.ZKAssign:
> master:60000-0x3456a48dd7d0223,
> quorum=hor13n04.gq1.ygridcore.net:2181,hor13n03.gq1.ygridcore.net:2181,hor13n20.gq1.ygridcore.net:2181,
> baseZNode=/hbase Creating (or updating) unassigned node 1588230740 with
> OFFLINE state
> 2014-04-16 18:31:26,323 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.AssignmentManager:
> Assigning hbase:meta,,1.1588230740 to
> hor13n04.gq1.ygridcore.net,60020,1397672685370
> 2014-04-16 18:31:26,323 INFO
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.RegionStates:
> Transitioned {1588230740 state=OFFLINE, ts=1397673086315,
> server=hor13n03.gq1.ygridcore.net,60020,1397672668647} to {1588230740
> state=PENDING_OPEN, ts=1397673086323,
> server=hor13n04.gq1.ygridcore.net,60020,1397672685370}
> 2014-04-16 18:31:28,337 DEBUG
> [MASTER_META_SERVER_OPERATIONS-hor13n02:60000-2] master.DeadServer: Finished
> processing hor13n03.gq1.ygridcore.net,60020,1397672668647
> {code}
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