[HBASE-16234] Expect and handle nulls when assigning replicas

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.0.0
• Component/s: Region Assignment
• Hadoop Flags: Reviewed
• Assignee: Yi Liang
• Reporter: Harsh J
• Created: 15/Jul/16 04:58
• Updated: 01/Aug/16 07:39
• Resolved: 01/Aug/16 03:24

Description

Observed this on a cluster:

FATAL org.apache.hadoop.hbase.master.HMaster: Unhandled exception. Starting shutdown. 
java.lang.NullPointerException 
at org.apache.hadoop.hbase.master.AssignmentManager.replicaRegionsNotRecordedInMeta(AssignmentManager.java:2799) 
at org.apache.hadoop.hbase.master.AssignmentManager.assignAllUserRegions(AssignmentManager.java:2778) 
at org.apache.hadoop.hbase.master.AssignmentManager.processDeadServersAndRegionsInTransition(AssignmentManager.java:638) 
at org.apache.hadoop.hbase.master.AssignmentManager.joinCluster(AssignmentManager.java:485) 
at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:723) 
at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:169) 
at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1481) 
at java.lang.Thread.run(Thread.java:745) 

It looks like FSTableDescriptors#get(…) can be expected to return null in some cases, but AssignmentManager.replicaRegionsNotRecordedInMeta(…) does not currently have any handling for such a possibility.