diff --git a/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala b/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala
index 3ace2364ed8ab..36e66b821cc41 100644
--- a/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala
+++ b/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala
@@ -22,7 +22,7 @@ import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.storage.BlockManagerId
 import org.apache.spark.scheduler.TaskScheduler
 
-case class Heartbeat(
+private[spark] case class Heartbeat(
     executorId: String,
     taskMetrics: Array[(Long, TaskMetrics)],
     blockManagerId: BlockManagerId)
@@ -31,7 +31,7 @@ case class Heartbeat(
 /**
  * Lives in the driver to receive heartbeats from executors..
  */
-class HeartbeatReceiver(scheduler: TaskScheduler) extends Actor {
+private[spark] class HeartbeatReceiver(scheduler: TaskScheduler) extends Actor {
   override def receive = {
     case Heartbeat(executorId, taskMetrics, blockManagerId) =>
       sender ! scheduler.executorHeartbeatReceived(executorId, taskMetrics, blockManagerId)
diff --git a/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala b/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
index 7e7efbb4ec182..43f754e522587 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
@@ -160,7 +160,9 @@ class DAGScheduler(
    * alive. Return true if the driver knows about the given block manager. Otherwise, return false,
    * indicating that the block manager should re-register.
    */
-  def executorHeartbeatReceived(execId: String, taskMetrics: Array[(Long, Int, TaskMetrics)],
+  def executorHeartbeatReceived(
+      execId: String,
+      taskMetrics: Array[(Long, Int, TaskMetrics)],
       blockManagerId: BlockManagerId): Boolean = {
     listenerBus.post(SparkListenerExecutorMetricsUpdate(execId, taskMetrics))
     implicit val timeout = Timeout(30 seconds)
diff --git a/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala b/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
index 4974ef988022b..d01d318633877 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
@@ -75,8 +75,11 @@ case class SparkListenerBlockManagerRemoved(blockManagerId: BlockManagerId)
 @DeveloperApi
 case class SparkListenerUnpersistRDD(rddId: Int) extends SparkListenerEvent
 
-case class SparkListenerExecutorMetricsUpdate(execId: String,
-  taskMetrics: Seq[(Long, Int, TaskMetrics)]) extends SparkListenerEvent
+@DeveloperApi
+case class SparkListenerExecutorMetricsUpdate(
+    execId: String,
+    taskMetrics: Seq[(Long, Int, TaskMetrics)])
+  extends SparkListenerEvent
 
 @DeveloperApi
 case class SparkListenerApplicationStart(appName: String, time: Long, sparkUser: String)
diff --git a/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala b/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
index eb95ec0064a65..6a7cfadd8b885 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
@@ -328,9 +328,11 @@ private[spark] class TaskSchedulerImpl(
    * alive. Return true if the driver knows about the given block manager. Otherwise, return false,
    * indicating that the block manager should re-register.
    */
-  override def executorHeartbeatReceived(execId: String, taskMetrics: Array[(Long, TaskMetrics)],
+  override def executorHeartbeatReceived(
+      execId: String,
+      taskMetrics: Array[(Long, TaskMetrics)],
       blockManagerId: BlockManagerId): Boolean = {
-    val metricsWithStageIds = taskMetrics.flatMap{
+    val metricsWithStageIds = taskMetrics.flatMap {
       case (id, metrics) => {
         taskIdToTaskSetId.get(id)
           .flatMap(activeTaskSets.get)
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedClusterMessage.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedClusterMessage.scala
index 8c5ca3ec6b131..6abf6d930c155 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedClusterMessage.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedClusterMessage.scala
@@ -21,8 +21,6 @@ import java.nio.ByteBuffer
 
 import org.apache.spark.TaskState.TaskState
 import org.apache.spark.util.{SerializableBuffer, Utils}
-import org.apache.spark.executor.TaskMetrics
-import org.apache.spark.storage.BlockManagerId
 
 private[spark] sealed trait CoarseGrainedClusterMessage extends Serializable
 
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/JobProgressListener.scala b/core/src/main/scala/org/apache/spark/ui/jobs/JobProgressListener.scala
index 61add1d786051..0df6541f04369 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/JobProgressListener.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/JobProgressListener.scala
@@ -113,7 +113,7 @@ class JobProgressListener(conf: SparkConf) extends SparkListener with Logging {
         new StageUIData
       })
       stageData.numActiveTasks += 1
-      stageData.taskData.put(taskInfo.taskId, new UIData.TaskUIData(taskInfo))
+      stageData.taskData.put(taskInfo.taskId, new TaskUIData(taskInfo))
     }
   }
 
@@ -160,14 +160,17 @@ class JobProgressListener(conf: SparkConf) extends SparkListener with Logging {
         updateAggregateMetrics(stageData, info.executorId, metrics.get, oldMetrics)
       }
 
-      val taskData = stageData.taskData.getOrElseUpdate(info.taskId, new UIData.TaskUIData(info))
+      val taskData = stageData.taskData.getOrElseUpdate(info.taskId, new TaskUIData(info))
       taskData.taskInfo = info
       taskData.taskMetrics = metrics
       taskData.errorMessage = errorMessage
     }
   }
 
-  def updateAggregateMetrics(stageData: StageUIData, execId: String, taskMetrics: TaskMetrics,
+  def updateAggregateMetrics(
+      stageData: StageUIData,
+      execId: String,
+      taskMetrics: TaskMetrics,
       oldMetrics: Option[TaskMetrics]) {
     val execSummary = stageData.executorSummary.getOrElseUpdate(execId, new ExecutorSummary)
 
@@ -205,7 +208,7 @@ class JobProgressListener(conf: SparkConf) extends SparkListener with Logging {
         new StageUIData
       })
       val taskData = stageData.taskData.get(taskId)
-      taskData.map{ t =>
+      taskData.map { t =>
         if (!t.taskInfo.finished) {
           updateAggregateMetrics(stageData, executorMetricsUpdate.execId, taskMetrics,
             t.taskMetrics)
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/UIData.scala b/core/src/main/scala/org/apache/spark/ui/jobs/UIData.scala
index 48b99cf851620..ecd3b918e0997 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/UIData.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/UIData.scala
@@ -55,7 +55,7 @@ private[jobs] object UIData {
     var executorSummary = new HashMap[String, ExecutorSummary]
   }
 
-  case class TaskUIData(
+  class TaskUIData(
       var taskInfo: TaskInfo,
       var taskMetrics: Option[TaskMetrics] = None,
       var errorMessage: Option[String] = None)
diff --git a/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala b/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala
index ef25f82c5aeda..feafd654e9e71 100644
--- a/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala
+++ b/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala
@@ -142,8 +142,12 @@ private[spark] object AkkaUtils extends Logging {
    * Send a message to the given actor and get its result within a default timeout, or
    * throw a SparkException if this fails.
    */
-  def askWithReply[T](message: Any, actor: ActorRef, retryAttempts: Int,
-                      retryInterval: Int, timeout: FiniteDuration): T = {
+  def askWithReply[T](
+      message: Any,
+      actor: ActorRef,
+      retryAttempts: Int,
+      retryInterval: Int,
+      timeout: FiniteDuration): T = {
     // TODO: Consider removing multiple attempts
     if (actor == null) {
       throw new SparkException("Error sending message as driverActor is null " +