From a2af3a76a22bf4e8e07396606927b58c6da7c771 Mon Sep 17 00:00:00 2001
From: Zhihong Yu <tedyu@apache.org>
Date: Fri, 19 Apr 2013 17:08:00 +0000
Subject: [PATCH] HBASE-8374 NullPointerException when launching the balancer
 due to unknown region location (Ted Yu)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1469954 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop/hbase/master/balancer/BaseLoadBalancer.java   | 9 ++++++++-
 .../hbase/master/balancer/StochasticLoadBalancer.java    | 2 +-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java
index 50c774f0cac..94149a5dbb5 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java
@@ -105,10 +105,15 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
       regionLocations = new int[numRegions][];
 
       int tableIndex = 0, serverIndex = 0, regionIndex = 0, regionPerServerIndex = 0;
+      // populate serversToIndex first
       for (Entry<ServerName, List<HRegionInfo>> entry : clusterState.entrySet()) {
         servers[serverIndex] = entry.getKey();
         regionsPerServer[serverIndex] = new int[entry.getValue().size()];
         serversToIndex.put(servers[serverIndex], Integer.valueOf(serverIndex));
+        serverIndex++;
+      }
+      serverIndex = 0;
+      for (Entry<ServerName, List<HRegionInfo>> entry : clusterState.entrySet()) {
         regionPerServerIndex = 0;
         for (HRegionInfo region : entry.getValue()) {
           byte[] tableName = region.getTableName();
@@ -142,7 +147,9 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
             List<ServerName> loc = regionFinder.getTopBlockLocations(region);
             regionLocations[regionIndex] = new int[loc.size()];
             for (int i=0; i < loc.size(); i++) {
-              regionLocations[regionIndex][i] = serversToIndex.get(loc.get(i));
+              regionLocations[regionIndex][i] =
+                  loc.get(i) == null ? -1 :
+                    (serversToIndex.get(loc.get(i)) == null ? -1 : serversToIndex.get(loc.get(i)));
             }
           }
 
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java
index 50e557046c0..330e9b18ad7 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/StochasticLoadBalancer.java
@@ -505,7 +505,7 @@ public class StochasticLoadBalancer extends BaseLoadBalancer {
 
       int index = -1;
       for (int j = 0; j < regionLocations.length; j++) {
-        if (regionLocations[j] == serverIndex) {
+        if (regionLocations[j] >= 0 && regionLocations[j] == serverIndex) {
           index = j;
           break;
         }