diff --git a/core/src/main/scala/org/apache/spark/MapOutputTracker.scala b/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
index e1a273593cce5..c45c5c90048f3 100644
--- a/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
+++ b/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
@@ -112,8 +112,8 @@ private[spark] abstract class MapOutputTracker(conf: SparkConf) extends Logging
   }
 
   /**
-   * Called from executors to get the server URIs and
-   * output sizes of the map outputs of a given shuffle
+   * Called from executors to get the server URIs and output sizes of the map outputs of
+   * a given shuffle.
    */
   def getServerStatuses(shuffleId: Int, reduceId: Int): Array[(BlockManagerId, Long)] = {
     val statuses = mapStatuses.get(shuffleId).orNull
@@ -218,10 +218,9 @@ private[spark] class MapOutputTrackerMaster(conf: SparkConf)
   private var cacheEpoch = epoch
 
   /**
-   * Timestamp based HashMap for storing mapStatuses and cached serialized statuses
-   * in the master, so that statuses are dropped only by explicit deregistering or
-   * by TTL-based cleaning (if set). Other than these two
-   * scenarios, nothing should be dropped from this HashMap.
+   * Timestamp based HashMap for storing mapStatuses and cached serialized statuses in the master,
+   * so that statuses are dropped only by explicit deregistering or by TTL-based cleaning (if set).
+   * Other than these two scenarios, nothing should be dropped from this HashMap.
    */
   protected val mapStatuses = new TimeStampedHashMap[Int, Array[MapStatus]]()
   private val cachedSerializedStatuses = new TimeStampedHashMap[Int, Array[Byte]]()
diff --git a/core/src/main/scala/org/apache/spark/SparkContext.scala b/core/src/main/scala/org/apache/spark/SparkContext.scala
index fe84b812ba8d0..79574c271cfb6 100644
--- a/core/src/main/scala/org/apache/spark/SparkContext.scala
+++ b/core/src/main/scala/org/apache/spark/SparkContext.scala
@@ -230,6 +230,7 @@ class SparkContext(
 
   private[spark] val cleaner = new ContextCleaner(this)
   cleaner.start()
+
   postEnvironmentUpdate()
 
   /** A default Hadoop Configuration for the Hadoop code (e.g. file systems) that we reuse. */
@@ -773,7 +774,7 @@ class SparkContext(
    * filesystems), an HTTP, HTTPS or FTP URI, or local:/path for a file on every worker node.
    */
   def addJar(path: String) {
-    if (path  == null) {
+    if (path == null) {
       logWarning("null specified as parameter to addJar")
     } else {
       var key = ""
diff --git a/core/src/main/scala/org/apache/spark/SparkEnv.scala b/core/src/main/scala/org/apache/spark/SparkEnv.scala
index 521182021dd4b..62398dc930993 100644
--- a/core/src/main/scala/org/apache/spark/SparkEnv.scala
+++ b/core/src/main/scala/org/apache/spark/SparkEnv.scala
@@ -185,6 +185,7 @@ object SparkEnv extends Logging {
     } else {
       new MapOutputTrackerWorker(conf)
     }
+
     // Have to assign trackerActor after initialization as MapOutputTrackerActor
     // requires the MapOutputTracker itself
     mapOutputTracker.trackerActor = registerOrLookup(
diff --git a/core/src/main/scala/org/apache/spark/broadcast/BroadcastFactory.scala b/core/src/main/scala/org/apache/spark/broadcast/BroadcastFactory.scala
index 850650951e603..9ff1675e76a5e 100644
--- a/core/src/main/scala/org/apache/spark/broadcast/BroadcastFactory.scala
+++ b/core/src/main/scala/org/apache/spark/broadcast/BroadcastFactory.scala
@@ -27,8 +27,8 @@ import org.apache.spark.SparkConf
  * entire Spark job.
  */
 trait BroadcastFactory {
-  def initialize(isDriver: Boolean, conf: SparkConf, securityMgr: SecurityManager): Unit
+  def initialize(isDriver: Boolean, conf: SparkConf, securityMgr: SecurityManager)
   def newBroadcast[T](value: T, isLocal: Boolean, id: Long): Broadcast[T]
   def unbroadcast(id: Long, removeFromDriver: Boolean)
-  def stop(): Unit
+  def stop()
 }
diff --git a/core/src/main/scala/org/apache/spark/broadcast/HttpBroadcast.scala b/core/src/main/scala/org/apache/spark/broadcast/HttpBroadcast.scala
index d5e3d60a5b2b7..d8981bb42e684 100644
--- a/core/src/main/scala/org/apache/spark/broadcast/HttpBroadcast.scala
+++ b/core/src/main/scala/org/apache/spark/broadcast/HttpBroadcast.scala
@@ -90,7 +90,7 @@ private[spark] object HttpBroadcast extends Logging {
   private var securityManager: SecurityManager = null
 
   // TODO: This shouldn't be a global variable so that multiple SparkContexts can coexist
-  val files = new TimeStampedHashSet[String]
+  private val files = new TimeStampedHashSet[String]
   private var cleaner: MetadataCleaner = null
 
   private val httpReadTimeout = TimeUnit.MILLISECONDS.convert(5, TimeUnit.MINUTES).toInt
@@ -195,7 +195,7 @@ private[spark] object HttpBroadcast extends Logging {
   def unpersist(id: Long, removeFromDriver: Boolean) = synchronized {
     SparkEnv.get.blockManager.master.removeBroadcast(id, removeFromDriver)
     if (removeFromDriver) {
-      val file = new File(broadcastDir, BroadcastBlockId(id).name)
+      val file = getFile(id)
       files.remove(file.toString)
       deleteBroadcastFile(file)
     }
@@ -217,10 +217,9 @@ private[spark] object HttpBroadcast extends Logging {
     }
   }
 
-  /** Delete the given broadcast file. */
   private def deleteBroadcastFile(file: File) {
     try {
-      if (!file.exists()) {
+      if (!file.exists) {
         logWarning("Broadcast file to be deleted does not exist: %s".format(file))
       } else if (file.delete()) {
         logInfo("Deleted broadcast file: %s".format(file))
@@ -229,7 +228,7 @@ private[spark] object HttpBroadcast extends Logging {
       }
     } catch {
       case e: Exception =>
-        logWarning("Exception while deleting broadcast file: %s".format(file), e)
+        logError("Exception while deleting broadcast file: %s".format(file), e)
     }
   }
 
diff --git a/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala b/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala
index ace71575f5390..ab280fad4e28f 100644
--- a/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala
+++ b/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala
@@ -72,7 +72,7 @@ private[spark] class TorrentBroadcast[T](@transient var value_ : T, isLocal: Boo
   }
 
   /**
-   * Remove all persisted state associated with this HTTP broadcast.
+   * Remove all persisted state associated with this Torrent broadcast.
    * @param removeFromDriver Whether to remove state from the driver.
    */
   override def unpersist(removeFromDriver: Boolean) {
@@ -177,13 +177,12 @@ private[spark] class TorrentBroadcast[T](@transient var value_ : T, isLocal: Boo
 }
 
 private[spark] object TorrentBroadcast extends Logging {
+  private lazy val BLOCK_SIZE = conf.getInt("spark.broadcast.blockSize", 4096) * 1024
   private var initialized = false
   private var conf: SparkConf = null
 
-  lazy val BLOCK_SIZE = conf.getInt("spark.broadcast.blockSize", 4096) * 1024
-
   def initialize(_isDriver: Boolean, conf: SparkConf) {
-    TorrentBroadcast.conf = conf //TODO: we might have to fix it in tests
+    TorrentBroadcast.conf = conf // TODO: we might have to fix it in tests
     synchronized {
       if (!initialized) {
         initialized = true
diff --git a/core/src/main/scala/org/apache/spark/rdd/RDD.scala b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
index e5638d0132e88..e8d36e6bfc810 100644
--- a/core/src/main/scala/org/apache/spark/rdd/RDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
@@ -158,7 +158,7 @@ abstract class RDD[T: ClassTag](
    */
   def unpersist(blocking: Boolean = true): RDD[T] = {
     logInfo("Removing RDD " + id + " from persistence list")
-    sc.unpersistRDD(this.id, blocking)
+    sc.unpersistRDD(id, blocking)
     storageLevel = StorageLevel.NONE
     this
   }
@@ -1128,4 +1128,5 @@ abstract class RDD[T: ClassTag](
   def toJavaRDD() : JavaRDD[T] = {
     new JavaRDD(this)(elementClassTag)
   }
+
 }
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 edef40e7309f6..f31f0580c36fe 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
@@ -1090,7 +1090,6 @@ class DAGScheduler(
       eventProcessActor ! StopDAGScheduler
     }
     taskScheduler.stop()
-    listenerBus.stop()
   }
 }
 
diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManager.scala b/core/src/main/scala/org/apache/spark/storage/BlockManager.scala
index 78dc32b4b1525..24ec8d3ab44bf 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManager.scala
@@ -49,8 +49,8 @@ private[spark] class BlockManager(
     maxMemory: Long,
     val conf: SparkConf,
     securityManager: SecurityManager,
-    mapOutputTracker: MapOutputTracker
-  ) extends Logging {
+    mapOutputTracker: MapOutputTracker)
+  extends Logging {
 
   val shuffleBlockManager = new ShuffleBlockManager(this)
   val diskBlockManager = new DiskBlockManager(shuffleBlockManager,
diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala b/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala
index 674322e3034c8..5c9ea88d6b1a4 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala
@@ -82,7 +82,7 @@ class BlockManagerMaster(var driverActor: ActorRef, conf: SparkConf) extends Log
 
   /**
    * Check if block manager master has a block. Note that this can be used to check for only
-   * those blocks that are expected to be reported to block manager master.
+   * those blocks that are reported to block manager master.
    */
   def contains(blockId: BlockId) = {
     !getLocations(blockId).isEmpty
diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterActor.scala b/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterActor.scala
index f83c26dafe2e9..3271d4f1375ef 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterActor.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterActor.scala
@@ -167,7 +167,7 @@ class BlockManagerMasterActor(val isLocal: Boolean, conf: SparkConf, listenerBus
    * from the executors, but not from the driver.
    */
   private def removeBroadcast(broadcastId: Long, removeFromDriver: Boolean) {
-    // TODO(aor): Consolidate usages of <driver>
+    // TODO: Consolidate usages of <driver>
     val removeMsg = RemoveBroadcast(broadcastId)
     blockManagerInfo.values
       .filter { info => removeFromDriver || info.blockManagerId.executorId != "<driver>" }
@@ -350,7 +350,6 @@ class BlockManagerMasterActor(val isLocal: Boolean, conf: SparkConf, listenerBus
     // Note that this logic will select the same node multiple times if there aren't enough peers
     Array.tabulate[BlockManagerId](size) { i => peers((selfIndex + i + 1) % peers.length) }.toSeq
   }
-
 }
 
 
diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManagerMessages.scala b/core/src/main/scala/org/apache/spark/storage/BlockManagerMessages.scala
index 1d3e94c4b6533..9a29c39a28ab1 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMessages.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMessages.scala
@@ -22,11 +22,9 @@ import java.io.{Externalizable, ObjectInput, ObjectOutput}
 import akka.actor.ActorRef
 
 private[storage] object BlockManagerMessages {
-
   //////////////////////////////////////////////////////////////////////////////////
   // Messages from the master to slaves.
   //////////////////////////////////////////////////////////////////////////////////
-
   sealed trait ToBlockManagerSlave
 
   // Remove a block from the slaves that have it. This can only be used to remove
@@ -50,7 +48,6 @@ private[storage] object BlockManagerMessages {
   //////////////////////////////////////////////////////////////////////////////////
   // Messages from slaves to the master.
   //////////////////////////////////////////////////////////////////////////////////
-
   sealed trait ToBlockManagerMaster
 
   case class RegisterBlockManager(
@@ -122,5 +119,4 @@ private[storage] object BlockManagerMessages {
 
   // For testing. Have the master ask all slaves for the given block's storage level.
   case class AskForStorageLevels(blockId: BlockId) extends ToBlockManagerMaster
-
 }
diff --git a/core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala b/core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala
index a57e6f710305a..fcad84669c79a 100644
--- a/core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala
@@ -90,7 +90,7 @@ private[spark] class DiskBlockManager(shuffleManager: ShuffleBlockManager, rootD
 
   def getFile(blockId: BlockId): File = getFile(blockId.name)
 
-  /** Check if disk block manager has a block */
+  /** Check if disk block manager has a block. */
   def containsBlock(blockId: BlockId): Boolean = {
     getBlockLocation(blockId).file.exists()
   }
diff --git a/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala b/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala
index cf83a60ffb9e8..06233153c56d4 100644
--- a/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/ShuffleBlockManager.scala
@@ -169,13 +169,13 @@ class ShuffleBlockManager(blockManager: BlockManager) extends Logging {
     throw new IllegalStateException("Failed to find shuffle block: " + id)
   }
 
-  /** Remove all the blocks / files and metadata related to a particular shuffle */
+  /** Remove all the blocks / files and metadata related to a particular shuffle. */
   def removeShuffle(shuffleId: ShuffleId) {
     removeShuffleBlocks(shuffleId)
     shuffleStates.remove(shuffleId)
   }
 
-  /** Remove all the blocks / files related to a particular shuffle */
+  /** Remove all the blocks / files related to a particular shuffle. */
   private def removeShuffleBlocks(shuffleId: ShuffleId) {
     shuffleStates.get(shuffleId) match {
       case Some(state) =>
diff --git a/core/src/main/scala/org/apache/spark/storage/ThreadingTest.scala b/core/src/main/scala/org/apache/spark/storage/ThreadingTest.scala
index 7b75215846a9a..a107c5182b3be 100644
--- a/core/src/main/scala/org/apache/spark/storage/ThreadingTest.scala
+++ b/core/src/main/scala/org/apache/spark/storage/ThreadingTest.scala
@@ -48,7 +48,7 @@ private[spark] object ThreadingTest {
         val block = (1 to blockSize).map(_ => Random.nextInt())
         val level = randomLevel()
         val startTime = System.currentTimeMillis()
-        manager.put(blockId, block.iterator, level, true)
+        manager.put(blockId, block.iterator, level, tellMaster = true)
         println("Pushed block " + blockId + " in " + (System.currentTimeMillis - startTime) + " ms")
         queue.add((blockId, block))
       }
diff --git a/core/src/main/scala/org/apache/spark/util/MetadataCleaner.scala b/core/src/main/scala/org/apache/spark/util/MetadataCleaner.scala
index 2ef853710a554..7ebed5105b9fd 100644
--- a/core/src/main/scala/org/apache/spark/util/MetadataCleaner.scala
+++ b/core/src/main/scala/org/apache/spark/util/MetadataCleaner.scala
@@ -78,15 +78,16 @@ private[spark] object MetadataCleaner {
     conf.getInt("spark.cleaner.ttl", -1)
   }
 
-  def getDelaySeconds(conf: SparkConf, cleanerType: MetadataCleanerType.MetadataCleanerType): Int =
-  {
-    conf.get(MetadataCleanerType.systemProperty(cleanerType), getDelaySeconds(conf).toString)
-      .toInt
+  def getDelaySeconds(
+      conf: SparkConf,
+      cleanerType: MetadataCleanerType.MetadataCleanerType): Int = {
+    conf.get(MetadataCleanerType.systemProperty(cleanerType), getDelaySeconds(conf).toString).toInt
   }
 
-  def setDelaySeconds(conf: SparkConf, cleanerType: MetadataCleanerType.MetadataCleanerType,
-      delay: Int)
-  {
+  def setDelaySeconds(
+      conf: SparkConf,
+      cleanerType: MetadataCleanerType.MetadataCleanerType,
+      delay: Int) {
     conf.set(MetadataCleanerType.systemProperty(cleanerType),  delay.toString)
   }
 
diff --git a/core/src/main/scala/org/apache/spark/util/TimeStampedWeakValueHashMap.scala b/core/src/main/scala/org/apache/spark/util/TimeStampedWeakValueHashMap.scala
index 09a6faf33ec60..9f3247a27ba38 100644
--- a/core/src/main/scala/org/apache/spark/util/TimeStampedWeakValueHashMap.scala
+++ b/core/src/main/scala/org/apache/spark/util/TimeStampedWeakValueHashMap.scala
@@ -17,14 +17,14 @@
 
 package org.apache.spark.util
 
-import scala.collection.{JavaConversions, immutable}
-
-import java.util
 import java.lang.ref.WeakReference
+import java.util
 import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.atomic.AtomicInteger
+
+import scala.collection.JavaConversions
 
 import org.apache.spark.Logging
-import java.util.concurrent.atomic.AtomicInteger
 
 private[util] case class TimeStampedWeakValue[T](timestamp: Long, weakValue: WeakReference[T]) {
   def this(timestamp: Long, value: T) = this(timestamp, new WeakReference[T](value))
diff --git a/core/src/test/scala/org/apache/spark/MapOutputTrackerSuite.scala b/core/src/test/scala/org/apache/spark/MapOutputTrackerSuite.scala
index b83033c35f6b7..6b2571cd9295e 100644
--- a/core/src/test/scala/org/apache/spark/MapOutputTrackerSuite.scala
+++ b/core/src/test/scala/org/apache/spark/MapOutputTrackerSuite.scala
@@ -96,7 +96,7 @@ class MapOutputTrackerSuite extends FunSuite with LocalSparkContext {
     assert(tracker.getServerStatuses(10, 0).isEmpty)
   }
 
-  test("master register shuffle and unregister mapoutput and fetch") {
+  test("master register shuffle and unregister map output and fetch") {
     val actorSystem = ActorSystem("test")
     val tracker = new MapOutputTrackerMaster(conf)
     tracker.trackerActor =
diff --git a/core/src/test/scala/org/apache/spark/storage/BlockManagerSuite.scala b/core/src/test/scala/org/apache/spark/storage/BlockManagerSuite.scala
index 04e64ee7a45b3..1f5bcca64fc39 100644
--- a/core/src/test/scala/org/apache/spark/storage/BlockManagerSuite.scala
+++ b/core/src/test/scala/org/apache/spark/storage/BlockManagerSuite.scala
@@ -28,8 +28,7 @@ import org.scalatest.concurrent.Timeouts._
 import org.scalatest.matchers.ShouldMatchers._
 import org.scalatest.time.SpanSugar._
 
-import org.apache.spark.{MapOutputTrackerMaster, SecurityManager, SparkConf, SparkContext}
-import org.apache.spark.{SecurityManager, SparkConf}
+import org.apache.spark.{MapOutputTrackerMaster, SecurityManager, SparkConf}
 import org.apache.spark.scheduler.LiveListenerBus
 import org.apache.spark.serializer.{JavaSerializer, KryoSerializer}
 import org.apache.spark.util.{AkkaUtils, ByteBufferInputStream, SizeEstimator, Utils}
diff --git a/core/src/test/scala/org/apache/spark/util/WrappedJavaHashMapSuite.scala b/core/src/test/scala/org/apache/spark/util/WrappedJavaHashMapSuite.scala
index 0b9847174ac84..f6e6a4c77c820 100644
--- a/core/src/test/scala/org/apache/spark/util/WrappedJavaHashMapSuite.scala
+++ b/core/src/test/scala/org/apache/spark/util/WrappedJavaHashMapSuite.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.util
 
-import java.util
 import java.lang.ref.WeakReference
+import java.util
 
 import scala.collection.mutable.{ArrayBuffer, HashMap, Map}
 import scala.util.Random