[HBASE-3627] NPE in EventHandler when region already reassigned

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 0.90.1
• Fix Version/s: 0.90.2
• Hadoop Flags: Reviewed
• Assignee: Michael Stack
• Reporter: Jean-Daniel Cryans
• Created: 12/Mar/11 00:13
• Updated: 20/Nov/15 12:43
• Resolved: 24/Mar/11 19:04

Description

When a region takes too long to open, it will try to update the unassigned znode and will fail on an ugly NPE like this:

DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign: regionserver:60020-0x22dc571dde04ca7 Attempting to transition node 0519dc3b62a569347526875048c37faa from RS_ZK_REGION_OPENING to RS_ZK_REGION_OPENING
DEBUG org.apache.hadoop.hbase.zookeeper.ZKUtil: regionserver:60020-0x22dc571dde04ca7 Unable to get data of znode /hbase/unassigned/0519dc3b62a569347526875048c37faa because node does not exist (not necessarily an error)
ERROR org.apache.hadoop.hbase.executor.EventHandler: Caught throwable while processing event M_RS_OPEN_REGION
java.lang.NullPointerException
at org.apache.hadoop.hbase.util.Writables.getWritable(Writables.java:75)
at org.apache.hadoop.hbase.executor.RegionTransitionData.fromBytes(RegionTransitionData.java:198)
at org.apache.hadoop.hbase.zookeeper.ZKAssign.transitionNode(ZKAssign.java:672)
at org.apache.hadoop.hbase.zookeeper.ZKAssign.retransitionNodeOpening(ZKAssign.java:585)
at org.apache.hadoop.hbase.regionserver.handler.OpenRegionHandler.tickleOpening(OpenRegionHandler.java:322)
at org.apache.hadoop.hbase.regionserver.handler.OpenRegionHandler.process(OpenRegionHandler.java:97)
at org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:151)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)

I think the region server in this case should be closing the region ASAP.