diff --git a/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/WorkerLauncher.scala b/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/WorkerLauncher.scala
index 99b824e1295a7d87b9e7753eb353eaf32c1f2673..191ef798d706aa5a770feb721ca84fe52b952edd 100644
--- a/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/WorkerLauncher.scala
+++ b/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/WorkerLauncher.scala
@@ -56,7 +56,7 @@ class WorkerLauncher(args: ApplicationMasterArguments, conf: Configuration) exte
   // This actor just working as a monitor to watch on Driver Actor.
   class MonitorActor(driverUrl: String) extends Actor {
 
-    var driver: ActorSelection = null
+    var driver: ActorSelection = _
 
     override def preStart() {
       logInfo("Listen to driver: " + driverUrl)
@@ -66,7 +66,7 @@ class WorkerLauncher(args: ApplicationMasterArguments, conf: Configuration) exte
 
     override def receive = {
       case x: DisassociatedEvent =>
-        logInfo("Driver terminated or disconnected! Shutting down.")
+        logInfo("Driver terminated or disconnected! Shutting down. $x")
         driverClosed = true
     }
   }
diff --git a/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala b/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
index 85ab08ef34db4738f53f95d3d68dadde555df3cb..8a9a73f5b4cd678a09b3b6898a946064b7b9dd08 100644
--- a/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
+++ b/yarn/2.2/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
@@ -42,7 +42,7 @@ import org.apache.hadoop.yarn.client.api.AMRMClient.ContainerRequest
 import org.apache.hadoop.yarn.util.{RackResolver, Records}
 
 
-object AllocationType extends Enumeration ("HOST", "RACK", "ANY") {
+object AllocationType extends Enumeration {
   type AllocationType = Value
   val HOST, RACK, ANY = Value
 }