From 686e77108a339516e4a78751fc4982072e171e97 Mon Sep 17 00:00:00 2001
From: Ted Yu <tedyu@apache.org>
Date: Fri, 17 Oct 2014 16:05:31 +0000
Subject: [PATCH] HBASE-12274 Race between RegionScannerImpl#nextInternal() and
 RegionScannerImpl#close() may produce null pointer exception

---
 .../java/org/apache/hadoop/hbase/regionserver/HRegion.java   | 4 ++++
 .../org/apache/hadoop/hbase/regionserver/RSRpcServices.java  | 5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
index 28c6cc50e65..67ff2cb2d6b 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
@@ -4108,6 +4108,10 @@ public class HRegion implements HeapSize, PropagatingConfigurationObserver { //
 
     @Override
     public boolean nextRaw(List<Cell> outResults, int limit) throws IOException {
+      if (storeHeap == null) {
+        // scanner is closed
+        throw new UnknownScannerException("Scanner was closed");
+      }
       boolean returnResult;
       if (outResults.isEmpty()) {
         // Usually outResults is empty. This is true when next is called
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
index eae6e960ea1..dc4bf7b7683 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java
@@ -2164,9 +2164,12 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
         if (rsh != null) {
           try {
             RegionScanner scanner = rsh.s;
+            LOG.warn(scannerName + " encountered " + ie.getMessage() + ", closing ...");
             scanner.close();
             regionServer.leases.cancelLease(scannerName);
-          } catch (IOException e) {}
+          } catch (IOException e) {
+           LOG.warn("Getting exception closing " + scannerName, e);
+          }
         }
       }
       throw new ServiceException(ie);