[HBASE-12274] Race between RegionScannerImpl#nextInternal() and RegionScannerImpl#close() may produce null pointer exception

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.98.6.1
• Fix Version/s: 0.98.8, 0.99.2
• Hadoop Flags: Reviewed
• Assignee: Ted Yu
• Reporter: Ted Yu
• Created: 15/Oct/14 19:35
• Updated: 06/Apr/18 17:54
• Resolved: 31/Oct/14 04:31

Description

I saw the following in region server log:

2014-10-15 03:28:36,976 ERROR [B.DefaultRpcServer.handler=0,queue=0,port=60020] ipc.RpcServer: Unexpected throwable object
java.lang.NullPointerException
  at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextInternal(HRegion.java:5023)
  at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:4932)
  at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextRaw(HRegion.java:4923)
  at org.apache.hadoop.hbase.regionserver.HRegionServer.scan(HRegionServer.java:3245)
  at org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$2.callBlockingMethod(ClientProtos.java:29994)
  at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2078)
  at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:108)
  at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:114)
  at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:94)
  at java.lang.Thread.run(Thread.java:745)

This is where the NPE happened:

        // Let's see what we have in the storeHeap.
        KeyValue current = this.storeHeap.peek();

The cause was race between nextInternal(called through nextRaw) and close methods.
nextRaw() is not synchronized.