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https://issues.apache.org/jira/browse/HBASE-4792?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jean-Daniel Cryans resolved HBASE-4792.
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Resolution: Fixed
Hadoop Flags: Reviewed
Committed to branch and trunk, thanks for looking at my code Stack.
> SplitRegionHandler doesn't care if it deletes the znode or not, leaves the
> parent region stuck offline
> ------------------------------------------------------------------------------------------------------
>
> Key: HBASE-4792
> URL: https://issues.apache.org/jira/browse/HBASE-4792
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.92.0
> Reporter: Jean-Daniel Cryans
> Assignee: Jean-Daniel Cryans
> Priority: Critical
> Fix For: 0.92.0, 0.94.0
>
> Attachments: HBASE-4792-0.92.patch
>
>
> Saw this on a little test cluster, really easy to trigger.
> First the master log:
> {quote}
> 2011-11-15 22:28:57,900 DEBUG
> org.apache.hadoop.hbase.master.handler.SplitRegionHandler: Handling SPLIT
> event for e5be6551c8584a6a1065466e520faf4e; deleting node
> 2011-11-15 22:28:57,900 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> master:62003-0x132f043bbde08c1 Deleting existing unassigned node for
> e5be6551c8584a6a1065466e520faf4e that is in expected state RS_ZK_REGION_SPLIT
> 2011-11-15 22:28:57,975 WARN org.apache.hadoop.hbase.zookeeper.ZKAssign:
> master:62003-0x132f043bbde08c1 Attempting to delete unassigned node in
> RS_ZK_REGION_SPLIT state but after verifying state, we got a version mismatch
> 2011-11-15 22:28:57,975 INFO
> org.apache.hadoop.hbase.master.handler.SplitRegionHandler: Handled SPLIT
> report);
> parent=TestTable,0001355346,1321396080924.e5be6551c8584a6a1065466e520faf4e.
> daughter
> a=TestTable,0001355346,1321396132414.df9b549eb594a1f8728608a2a431224a.daughter
> b=TestTable,0001368082,1321396132414.de861596db4337dc341138f26b9c8bc2.
> ...
> 2011-11-15 22:28:58,052 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_SPLIT, server=sv4r28s44,62023,1321395865619,
> region=e5be6551c8584a6a1065466e520faf4e
> 2011-11-15 22:28:58,052 WARN
> org.apache.hadoop.hbase.master.AssignmentManager: Region
> e5be6551c8584a6a1065466e520faf4e not found on server
> sv4r28s44,62023,1321395865619; failed processing
> 2011-11-15 22:28:58,052 WARN
> org.apache.hadoop.hbase.master.AssignmentManager: Received SPLIT for region
> e5be6551c8584a6a1065466e520faf4e from server sv4r28s44,62023,1321395865619
> but it doesn't exist anymore, probably already processed its split
> (repeated forever)
> {quote}
> The master processes the split but when it calls ZKAssign.deleteNode it
> doesn't check the boolean that's returned. In this case it was false. So for
> the master the split was completed, but for the region server it's another
> story:
> {quote}
> 2011-11-15 22:28:57,661 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> regionserver:62023-0x132f043bbde08d3 Attempting to transition node
> e5be6551c8584a6a1065466e520faf4e from RS_ZK_REGION_SPLITTING to
> RS_ZK_REGION_SPLIT
> 2011-11-15 22:28:57,775 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> regionserver:62023-0x132f043bbde08d3 Successfully transitioned node
> e5be6551c8584a6a1065466e520faf4e from RS_ZK_REGION_SPLITTING to
> RS_ZK_REGION_SPLIT
> 2011-11-15 22:28:57,775 INFO
> org.apache.hadoop.hbase.regionserver.SplitTransaction: Still waiting on the
> master to process the split for e5be6551c8584a6a1065466e520faf4e
> 2011-11-15 22:28:57,876 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> regionserver:62023-0x132f043bbde08d3 Attempting to transition node
> e5be6551c8584a6a1065466e520faf4e from RS_ZK_REGION_SPLIT to RS_ZK_REGION_SPLIT
> 2011-11-15 22:28:57,967 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> regionserver:62023-0x132f043bbde08d3 Successfully transitioned node
> e5be6551c8584a6a1065466e520faf4e from RS_ZK_REGION_SPLIT to RS_ZK_REGION_SPLIT
> 2011-11-15 22:28:58,067 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> regionserver:62023-0x132f043bbde08d3 Attempting to transition node
> e5be6551c8584a6a1065466e520faf4e from RS_ZK_REGION_SPLIT to RS_ZK_REGION_SPLIT
> 2011-11-15 22:28:58,108 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> regionserver:62023-0x132f043bbde08d3 Successfully transitioned node
> e5be6551c8584a6a1065466e520faf4e from RS_ZK_REGION_SPLIT to RS_ZK_REGION_SPLIT
> (printed forever)
> {quote}
> Since the znode isn't really deleted, it thinks the master just haven't got
> to process its region thus waits which leaves the region *unavailable*.
> We need to just retry the delete master-side ASAP since the RS will wait
> 100ms between retries.
> At the same time, it would be nice if ZKAssign.deleteNode always printed out
> the name of the region in its messages because it took me a while to see that
> the delete didn't take affect while looking at a grep.
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