From a9594c61bb8ca9e61e367988d3012a4615026090 Mon Sep 17 00:00:00 2001
From: Wangda Tan <wangda@apache.org>
Date: Wed, 30 Dec 2015 15:34:39 -0800
Subject: [PATCH] YARN-4510. Fix SLS startup failure caused by NPE. (Bibin A
 Chundatt via wangda)

(cherry picked from commit 6eefae1b33928486e7a8572e14eaf00b83f2acfc)
---
 .../apache/hadoop/yarn/sls/scheduler/RMNodeWrapper.java   | 3 ++-
 .../yarn/sls/scheduler/ResourceSchedulerWrapper.java      | 8 ++++++++
 hadoop-yarn-project/CHANGES.txt                           | 2 ++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/RMNodeWrapper.java b/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/RMNodeWrapper.java
index a082e20a1ee..2e9cccb2778 100644
--- a/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/RMNodeWrapper.java
+++ b/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/RMNodeWrapper.java
@@ -172,10 +172,11 @@ public void updateNodeHeartbeatResponseForContainersDecreasing(
     // TODO Auto-generated method stub
   }
 
+  @SuppressWarnings("unchecked")
   @Override
   public List<Container> pullNewlyIncreasedContainers() {
     // TODO Auto-generated method stub
-    return null;
+    return Collections.EMPTY_LIST;
   }
 
   @Override
diff --git a/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/ResourceSchedulerWrapper.java b/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/ResourceSchedulerWrapper.java
index fce220bf79e..106525d915c 100644
--- a/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/ResourceSchedulerWrapper.java
+++ b/hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/scheduler/ResourceSchedulerWrapper.java
@@ -819,6 +819,14 @@ public void serviceInit(Configuration conf) throws Exception {
     ((AbstractYarnScheduler<SchedulerApplicationAttempt, SchedulerNode>)
         scheduler).init(conf);
     super.serviceInit(conf);
+    initScheduler(conf);
+  }
+
+  private synchronized void initScheduler(Configuration configuration) throws
+  IOException {
+    this.applications =
+        new ConcurrentHashMap<ApplicationId,
+        SchedulerApplication<SchedulerApplicationAttempt>>();
   }
 
   @SuppressWarnings("unchecked")
diff --git a/hadoop-yarn-project/CHANGES.txt b/hadoop-yarn-project/CHANGES.txt
index 4c8eecb7793..b551aae82ac 100644
--- a/hadoop-yarn-project/CHANGES.txt
+++ b/hadoop-yarn-project/CHANGES.txt
@@ -1260,6 +1260,8 @@ Release 2.7.3 - UNRELEASED
 
     YARN-4315. NaN in Queue percentage for cluster apps page. (Bibin A Chundatt via wangda)
 
+    YARN-4510. Fix SLS startup failure caused by NPE. (Bibin A Chundatt via wangda)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES