diff --git a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
index 67ec95c8fc04f..7e75e5b602665 100644
--- a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
+++ b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMaster.scala
@@ -39,6 +39,9 @@ import org.apache.spark.{Logging, SecurityManager, SparkConf, SparkContext}
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.util.Utils
 
+/**
+ * An application master that runs the users driver program and allocates executors.
+ */
 class ApplicationMaster(args: ApplicationMasterArguments, conf: Configuration,
                         sparkConf: SparkConf) extends Logging {
 
diff --git a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
index 7b0e020263835..485e2d2061b7d 100644
--- a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
+++ b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
@@ -34,6 +34,12 @@ import org.apache.spark.util.{Utils, AkkaUtils}
 import org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend
 import org.apache.spark.scheduler.SplitInfo
 
+/**
+ * An application master that allocates executors on behalf of a driver that is running outside
+ * the cluster.
+ *
+ * This is used only in yarn-client mode.
+ */
 class ExecutorLauncher(args: ApplicationMasterArguments, conf: Configuration, sparkConf: SparkConf)
   extends Logging {
 
diff --git a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
index 2056667af50cb..92fe297808375 100644
--- a/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
+++ b/yarn/alpha/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
@@ -54,6 +54,10 @@ object AllocationType extends Enumeration {
 // Note that right now, we assume all node asks as uniform in terms of capabilities and priority
 // Refer to http://developer.yahoo.com/blogs/hadoop/posts/2011/03/mapreduce-nextgen-scheduler/ for
 // more info on how we are requesting for containers.
+
+/**
+ * Acquires resources for executors from a ResourceManager and launches executors in new containers.
+ */
 private[yarn] class YarnAllocationHandler(
     val conf: Configuration,
     val resourceManager: AMRMProtocol, 
diff --git a/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala b/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
index 350c242456042..f41cef18cc9a7 100644
--- a/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
+++ b/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/ExecutorLauncher.scala
@@ -36,7 +36,8 @@ import org.apache.hadoop.yarn.client.api.AMRMClient
 import org.apache.hadoop.yarn.client.api.AMRMClient.ContainerRequest
 
 /**
- * An application master that allocates executors on behalf of a driver that is running outside the cluster.
+ * An application master that allocates executors on behalf of a driver that is running outside
+ * the cluster.
  *
  * This is used only in yarn-client mode.
  */
diff --git a/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala b/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
index bf4c647fcafbc..3c80dce2d702d 100644
--- a/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
+++ b/yarn/stable/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocationHandler.scala
@@ -58,7 +58,7 @@ object AllocationType extends Enumeration {
 // more info on how we are requesting for containers.
 
 /**
- * Acquires resources for executors from a ResourceMAnager and launches executors in new containers.
+ * Acquires resources for executors from a ResourceManager and launches executors in new containers.
  */
 private[yarn] class YarnAllocationHandler(
     val conf: Configuration,