[SPARK-3873][CORE] Import ordering fixes.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #10578 from vanzin/SPARK-3873-core.

158 files changed, 246 insertions, 250 deletions

diff --git a/core/src/main/scala/org/apache/spark/ContextCleaner.scala b/core/src/main/scala/org/apache/spark/ContextCleaner.scala
index bc732535fe..4628093b91 100644
--- a/core/src/main/scala/org/apache/spark/ContextCleaner.scala
+++ b/core/src/main/scala/org/apache/spark/ContextCleaner.scala
@@ -18,7 +18,7 @@
 package org.apache.spark
 
 import java.lang.ref.{ReferenceQueue, WeakReference}
-import java.util.concurrent.{TimeUnit, ScheduledExecutorService}
+import java.util.concurrent.{ScheduledExecutorService, TimeUnit}
 
 import scala.collection.mutable.{ArrayBuffer, SynchronizedBuffer}
 
diff --git a/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala b/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
index 4926cafaed..3431fc13dc 100644
--- a/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
+++ b/core/src/main/scala/org/apache/spark/ExecutorAllocationManager.scala
@@ -24,9 +24,9 @@ import scala.util.control.ControlThrowable
 
 import com.codahale.metrics.{Gauge, MetricRegistry}
 
-import org.apache.spark.scheduler._
 import org.apache.spark.metrics.source.Source
-import org.apache.spark.util.{ThreadUtils, Clock, SystemClock, Utils}
+import org.apache.spark.scheduler._
+import org.apache.spark.util.{Clock, SystemClock, ThreadUtils, Utils}
 
 /**
  * An agent that dynamically allocates and removes executors based on the workload.
diff --git a/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala b/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala
index 1f1f0b75de..e03977828b 100644
--- a/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala
+++ b/core/src/main/scala/org/apache/spark/HeartbeatReceiver.scala
@@ -23,9 +23,9 @@ import scala.collection.mutable
 import scala.concurrent.Future
 
 import org.apache.spark.executor.TaskMetrics
-import org.apache.spark.rpc.{ThreadSafeRpcEndpoint, RpcEnv, RpcCallContext}
-import org.apache.spark.storage.BlockManagerId
+import org.apache.spark.rpc.{RpcCallContext, RpcEnv, ThreadSafeRpcEndpoint}
 import org.apache.spark.scheduler._
+import org.apache.spark.storage.BlockManagerId
 import org.apache.spark.util.{Clock, SystemClock, ThreadUtils, Utils}
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/HttpServer.scala b/core/src/main/scala/org/apache/spark/HttpServer.scala
index faa3ef3d75..3c808420c8 100644
--- a/core/src/main/scala/org/apache/spark/HttpServer.scala
+++ b/core/src/main/scala/org/apache/spark/HttpServer.scala
@@ -19,18 +19,17 @@ package org.apache.spark
 
 import java.io.File
 
-import org.eclipse.jetty.server.ssl.SslSocketConnector
-import org.eclipse.jetty.util.security.{Constraint, Password}
-import org.eclipse.jetty.security.authentication.DigestAuthenticator
 import org.eclipse.jetty.security.{ConstraintMapping, ConstraintSecurityHandler, HashLoginService}
+import org.eclipse.jetty.security.authentication.DigestAuthenticator
 import org.eclipse.jetty.server.Server
 import org.eclipse.jetty.server.bio.SocketConnector
+import org.eclipse.jetty.server.ssl.SslSocketConnector
 import org.eclipse.jetty.servlet.{DefaultServlet, ServletContextHandler, ServletHolder}
+import org.eclipse.jetty.util.security.{Constraint, Password}
 import org.eclipse.jetty.util.thread.QueuedThreadPool
 
 import org.apache.spark.util.Utils
 
-
 /**
  * Exception type thrown by HttpServer when it is in the wrong state for an operation.
  */
diff --git a/core/src/main/scala/org/apache/spark/MapOutputTracker.scala b/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
index 72355cdfa6..8670f705cd 100644
--- a/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
+++ b/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
@@ -26,7 +26,7 @@ import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet, Map}
 import scala.reflect.ClassTag
 
-import org.apache.spark.rpc.{RpcEndpointRef, RpcEnv, RpcCallContext, RpcEndpoint}
+import org.apache.spark.rpc.{RpcCallContext, RpcEndpoint, RpcEndpointRef, RpcEnv}
 import org.apache.spark.scheduler.MapStatus
 import org.apache.spark.shuffle.MetadataFetchFailedException
 import org.apache.spark.storage.{BlockId, BlockManagerId, ShuffleBlockId}
diff --git a/core/src/main/scala/org/apache/spark/Partitioner.scala b/core/src/main/scala/org/apache/spark/Partitioner.scala
index ef9a2dab1c..a7c2790c83 100644
--- a/core/src/main/scala/org/apache/spark/Partitioner.scala
+++ b/core/src/main/scala/org/apache/spark/Partitioner.scala
@@ -21,13 +21,13 @@ import java.io.{IOException, ObjectInputStream, ObjectOutputStream}
 
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
-import scala.reflect.{ClassTag, classTag}
+import scala.reflect.{classTag, ClassTag}
 import scala.util.hashing.byteswap32
 
 import org.apache.spark.rdd.{PartitionPruningRDD, RDD}
 import org.apache.spark.serializer.JavaSerializer
 import org.apache.spark.util.{CollectionsUtils, Utils}
-import org.apache.spark.util.random.{XORShiftRandom, SamplingUtils}
+import org.apache.spark.util.random.{SamplingUtils, XORShiftRandom}
 
 /**
  * An object that defines how the elements in a key-value pair RDD are partitioned by key.
diff --git a/core/src/main/scala/org/apache/spark/SparkConf.scala b/core/src/main/scala/org/apache/spark/SparkConf.scala
index ff2c4c34c0..340e1f7824 100644
--- a/core/src/main/scala/org/apache/spark/SparkConf.scala
+++ b/core/src/main/scala/org/apache/spark/SparkConf.scala
@@ -22,7 +22,7 @@ import java.util.concurrent.ConcurrentHashMap
 import scala.collection.JavaConverters._
 import scala.collection.mutable.LinkedHashSet
 
-import org.apache.avro.{SchemaNormalization, Schema}
+import org.apache.avro.{Schema, SchemaNormalization}
 
 import org.apache.spark.serializer.KryoSerializer
 import org.apache.spark.util.Utils
diff --git a/core/src/main/scala/org/apache/spark/SparkContext.scala b/core/src/main/scala/org/apache/spark/SparkContext.scala
index 87301202de..4a99c0b081 100644
--- a/core/src/main/scala/org/apache/spark/SparkContext.scala
+++ b/core/src/main/scala/org/apache/spark/SparkContext.scala
@@ -17,20 +17,19 @@
 
 package org.apache.spark
 
-import scala.language.implicitConversions
-
 import java.io._
 import java.lang.reflect.Constructor
 import java.net.URI
 import java.util.{Arrays, Properties, UUID}
-import java.util.concurrent.atomic.{AtomicReference, AtomicBoolean, AtomicInteger}
+import java.util.concurrent.atomic.{AtomicBoolean, AtomicInteger, AtomicReference}
 import java.util.UUID.randomUUID
 
 import scala.collection.JavaConverters._
 import scala.collection.Map
 import scala.collection.generic.Growable
 import scala.collection.mutable.HashMap
-import scala.reflect.{ClassTag, classTag}
+import scala.language.implicitConversions
+import scala.reflect.{classTag, ClassTag}
 import scala.util.control.NonFatal
 
 import org.apache.commons.lang.SerializationUtils
@@ -42,27 +41,26 @@ import org.apache.hadoop.mapred.{FileInputFormat, InputFormat, JobConf, Sequence
   TextInputFormat}
 import org.apache.hadoop.mapreduce.{InputFormat => NewInputFormat, Job => NewHadoopJob}
 import org.apache.hadoop.mapreduce.lib.input.{FileInputFormat => NewFileInputFormat}
-
 import org.apache.mesos.MesosNativeLibrary
 
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.broadcast.Broadcast
 import org.apache.spark.deploy.{LocalSparkCluster, SparkHadoopUtil}
-import org.apache.spark.input.{StreamInputFormat, PortableDataStream, WholeTextFileInputFormat,
-  FixedLengthBinaryInputFormat}
+import org.apache.spark.input.{FixedLengthBinaryInputFormat, PortableDataStream, StreamInputFormat,
+  WholeTextFileInputFormat}
 import org.apache.spark.io.CompressionCodec
 import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.partial.{ApproximateEvaluator, PartialResult}
 import org.apache.spark.rdd._
 import org.apache.spark.rpc.RpcEndpointRef
 import org.apache.spark.scheduler._
-import org.apache.spark.scheduler.cluster.{CoarseGrainedSchedulerBackend,
-  SparkDeploySchedulerBackend, SimrSchedulerBackend}
+import org.apache.spark.scheduler.cluster.{CoarseGrainedSchedulerBackend, SimrSchedulerBackend,
+  SparkDeploySchedulerBackend}
 import org.apache.spark.scheduler.cluster.mesos.{CoarseMesosSchedulerBackend, MesosSchedulerBackend}
 import org.apache.spark.scheduler.local.LocalBackend
 import org.apache.spark.storage._
 import org.apache.spark.storage.BlockManagerMessages.TriggerThreadDump
-import org.apache.spark.ui.{SparkUI, ConsoleProgressBar}
+import org.apache.spark.ui.{ConsoleProgressBar, SparkUI}
 import org.apache.spark.ui.jobs.JobProgressListener
 import org.apache.spark.util._
 
diff --git a/core/src/main/scala/org/apache/spark/SparkEnv.scala b/core/src/main/scala/org/apache/spark/SparkEnv.scala
index b98cc964ed..ec43be0e2f 100644
--- a/core/src/main/scala/org/apache/spark/SparkEnv.scala
+++ b/core/src/main/scala/org/apache/spark/SparkEnv.scala
@@ -29,12 +29,12 @@ import com.google.common.collect.MapMaker
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.api.python.PythonWorkerFactory
 import org.apache.spark.broadcast.BroadcastManager
-import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.memory.{MemoryManager, StaticMemoryManager, UnifiedMemoryManager}
+import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.network.BlockTransferService
 import org.apache.spark.network.netty.NettyBlockTransferService
-import org.apache.spark.rpc.{RpcEndpointRef, RpcEndpoint, RpcEnv}
-import org.apache.spark.scheduler.{OutputCommitCoordinator, LiveListenerBus}
+import org.apache.spark.rpc.{RpcEndpoint, RpcEndpointRef, RpcEnv}
+import org.apache.spark.scheduler.{LiveListenerBus, OutputCommitCoordinator}
 import org.apache.spark.scheduler.OutputCommitCoordinator.OutputCommitCoordinatorEndpoint
 import org.apache.spark.serializer.Serializer
 import org.apache.spark.shuffle.ShuffleManager
diff --git a/core/src/main/scala/org/apache/spark/SparkHadoopWriter.scala b/core/src/main/scala/org/apache/spark/SparkHadoopWriter.scala
index dd400b8ae8..5864786062 100644
--- a/core/src/main/scala/org/apache/spark/SparkHadoopWriter.scala
+++ b/core/src/main/scala/org/apache/spark/SparkHadoopWriter.scala
@@ -22,9 +22,9 @@ import java.text.NumberFormat
 import java.text.SimpleDateFormat
 import java.util.Date
 
-import org.apache.hadoop.mapred._
 import org.apache.hadoop.fs.FileSystem
 import org.apache.hadoop.fs.Path
+import org.apache.hadoop.mapred._
 import org.apache.hadoop.mapreduce.TaskType
 
 import org.apache.spark.mapred.SparkHadoopMapRedUtil
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
index 87deaf20e2..91dc18697c 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.api.java
 
-import java.util.{Comparator, List => JList, Map => JMap}
 import java.lang.{Iterable => JIterable}
+import java.util.{Comparator, List => JList, Map => JMap}
 
 import scala.collection.JavaConverters._
 import scala.language.implicitConversions
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
index 9cf68672be..6d3485d88a 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
@@ -19,7 +19,7 @@ package org.apache.spark.api.java
 
 import java.{lang => jl}
 import java.lang.{Iterable => JIterable, Long => JLong}
-import java.util.{Comparator, List => JList, Iterator => JIterator}
+import java.util.{Comparator, Iterator => JIterator, List => JList}
 
 import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala b/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala
index 9f5b89bb4b..9990b22e14 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala
@@ -27,7 +27,6 @@ import scala.reflect.ClassTag
 
 import com.google.common.base.Optional
 import org.apache.hadoop.conf.Configuration
-import org.apache.spark.input.PortableDataStream
 import org.apache.hadoop.mapred.{InputFormat, JobConf}
 import org.apache.hadoop.mapreduce.{InputFormat => NewInputFormat}
 
@@ -35,6 +34,7 @@ import org.apache.spark._
 import org.apache.spark.AccumulatorParam._
 import org.apache.spark.api.java.JavaSparkContext.fakeClassTag
 import org.apache.spark.broadcast.Broadcast
+import org.apache.spark.input.PortableDataStream
 import org.apache.spark.rdd.{EmptyRDD, HadoopRDD, NewHadoopRDD, RDD}
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaSparkStatusTracker.scala b/core/src/main/scala/org/apache/spark/api/java/JavaSparkStatusTracker.scala
index 3300cad9ef..99ca3c77cc 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaSparkStatusTracker.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaSparkStatusTracker.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.api.java
 
-import org.apache.spark.{SparkStageInfo, SparkJobInfo, SparkContext}
+import org.apache.spark.{SparkContext, SparkJobInfo, SparkStageInfo}
 
 /**
  * Low-level status reporting APIs for monitoring job and stage progress.
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala b/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala
index 8f9647eea9..b2a4d053fa 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaUtils.scala
@@ -17,13 +17,13 @@
 
 package org.apache.spark.api.java
 
+import java.{util => ju}
 import java.util.Map.Entry
 
-import com.google.common.base.Optional
-
-import java.{util => ju}
 import scala.collection.mutable
 
+import com.google.common.base.Optional
+
 private[spark] object JavaUtils {
   def optionToOptional[T](option: Option[T]): Optional[T] =
     option match {
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala b/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
index 8464b578ed..f12e2dfafa 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
@@ -19,7 +19,7 @@ package org.apache.spark.api.python
 
 import java.io._
 import java.net._
-import java.util.{Collections, ArrayList => JArrayList, List => JList, Map => JMap}
+import java.util.{ArrayList => JArrayList, Collections, List => JList, Map => JMap}
 
 import scala.collection.JavaConverters._
 import scala.collection.mutable
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala b/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala
index 292ac4cfc3..2d97cd9a9a 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala
@@ -24,7 +24,7 @@ import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.SparkContext
-import org.apache.spark.api.java.{JavaSparkContext, JavaRDD}
+import org.apache.spark.api.java.{JavaRDD, JavaSparkContext}
 
 private[spark] object PythonUtils {
   /** Get the PYTHONPATH for PySpark, either from SPARK_HOME, if it is set, or from our JAR */
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala b/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala
index 7039b734d2..a2a2f89f1e 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.api.python
 
-import java.io.{DataOutputStream, DataInputStream, InputStream, OutputStreamWriter}
+import java.io.{DataInputStream, DataOutputStream, InputStream, OutputStreamWriter}
 import java.net.{InetAddress, ServerSocket, Socket, SocketException}
 import java.util.Arrays
 
diff --git a/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala b/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala
index fd27276e70..b0d858486b 100644
--- a/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala
@@ -20,16 +20,15 @@ package org.apache.spark.api.python
 import java.nio.ByteOrder
 import java.util.{ArrayList => JArrayList}
 
-import org.apache.spark.api.java.JavaRDD
-
 import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.util.Failure
 import scala.util.Try
 
-import net.razorvine.pickle.{Unpickler, Pickler}
+import net.razorvine.pickle.{Pickler, Unpickler}
 
 import org.apache.spark.{Logging, SparkException}
+import org.apache.spark.api.java.JavaRDD
 import org.apache.spark.rdd.RDD
 
 /** Utilities for serialization / deserialization between Python and Java, using Pickle. */
diff --git a/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala b/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala
index ee1fb056f0..9549784aea 100644
--- a/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala
@@ -17,13 +17,12 @@
 
 package org.apache.spark.api.python
 
-import java.io.{DataOutput, DataInput}
 import java.{util => ju}
+import java.io.{DataInput, DataOutput}
 
 import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
-
 import org.apache.hadoop.io._
 import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat
 
diff --git a/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala b/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala
index 0095548c46..9bddd7248c 100644
--- a/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala
@@ -22,8 +22,8 @@ import java.io.{ByteArrayInputStream, ByteArrayOutputStream, DataInputStream, Da
 import scala.collection.mutable.HashMap
 import scala.language.existentials
 
-import io.netty.channel.ChannelHandler.Sharable
 import io.netty.channel.{ChannelHandlerContext, SimpleChannelInboundHandler}
+import io.netty.channel.ChannelHandler.Sharable
 
 import org.apache.spark.Logging
 import org.apache.spark.api.r.SerDe._
diff --git a/core/src/main/scala/org/apache/spark/api/r/RRDD.scala b/core/src/main/scala/org/apache/spark/api/r/RRDD.scala
index 7509b3d3f4..401f362fee 100644
--- a/core/src/main/scala/org/apache/spark/api/r/RRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/RRDD.scala
@@ -19,8 +19,7 @@ package org.apache.spark.api.r
 
 import java.io._
 import java.net.{InetAddress, ServerSocket}
-import java.util.Arrays
-import java.util.{Map => JMap}
+import java.util.{Arrays, Map => JMap}
 
 import scala.collection.JavaConverters._
 import scala.io.Source
diff --git a/core/src/main/scala/org/apache/spark/api/r/SerDe.scala b/core/src/main/scala/org/apache/spark/api/r/SerDe.scala
index da126bac7a..af815f885e 100644
--- a/core/src/main/scala/org/apache/spark/api/r/SerDe.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/SerDe.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.api.r
 
 import java.io.{DataInputStream, DataOutputStream}
-import java.sql.{Timestamp, Date, Time}
+import java.sql.{Date, Time, Timestamp}
 
 import scala.collection.JavaConverters._
 import scala.collection.mutable.WrappedArray
diff --git a/core/src/main/scala/org/apache/spark/broadcast/Broadcast.scala b/core/src/main/scala/org/apache/spark/broadcast/Broadcast.scala
index 12d79f6ed3..0d68872dcb 100644
--- a/core/src/main/scala/org/apache/spark/broadcast/Broadcast.scala
+++ b/core/src/main/scala/org/apache/spark/broadcast/Broadcast.scala
@@ -19,12 +19,12 @@ package org.apache.spark.broadcast
 
 import java.io.Serializable
 
-import org.apache.spark.SparkException
+import scala.reflect.ClassTag
+
 import org.apache.spark.Logging
+import org.apache.spark.SparkException
 import org.apache.spark.util.Utils
 
-import scala.reflect.ClassTag
-
 /**
  * A broadcast variable. Broadcast variables allow the programmer to keep a read-only variable
  * cached on each machine rather than shipping a copy of it with tasks. They can be used, for
diff --git a/core/src/main/scala/org/apache/spark/broadcast/BroadcastManager.scala b/core/src/main/scala/org/apache/spark/broadcast/BroadcastManager.scala
index 61343607a1..be416c4f74 100644
--- a/core/src/main/scala/org/apache/spark/broadcast/BroadcastManager.scala
+++ b/core/src/main/scala/org/apache/spark/broadcast/BroadcastManager.scala
@@ -21,8 +21,7 @@ import java.util.concurrent.atomic.AtomicLong
 
 import scala.reflect.ClassTag
 
-import org.apache.spark.{Logging, SparkConf, SecurityManager}
-
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 
 private[spark] class BroadcastManager(
     val isDriver: Boolean,
diff --git a/core/src/main/scala/org/apache/spark/deploy/Client.scala b/core/src/main/scala/org/apache/spark/deploy/Client.scala
index 328a1bb84f..63a20ab41a 100644
--- a/core/src/main/scala/org/apache/spark/deploy/Client.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/Client.scala
@@ -24,11 +24,11 @@ import scala.util.{Failure, Success}
 
 import org.apache.log4j.{Level, Logger}
 
-import org.apache.spark.rpc.{RpcEndpointRef, RpcAddress, RpcEnv, ThreadSafeRpcEndpoint}
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.DeployMessages._
 import org.apache.spark.deploy.master.{DriverState, Master}
-import org.apache.spark.util.{ThreadUtils, SparkExitCode, Utils}
+import org.apache.spark.rpc.{RpcAddress, RpcEndpointRef, RpcEnv, ThreadSafeRpcEndpoint}
+import org.apache.spark.util.{SparkExitCode, ThreadUtils, Utils}
 
 /**
  * Proxy that relays messages to the driver.
diff --git a/core/src/main/scala/org/apache/spark/deploy/ClientArguments.scala b/core/src/main/scala/org/apache/spark/deploy/ClientArguments.scala
index 72cc330a39..255420182b 100644
--- a/core/src/main/scala/org/apache/spark/deploy/ClientArguments.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/ClientArguments.scala
@@ -22,6 +22,7 @@ import java.net.{URI, URISyntaxException}
 import scala.collection.mutable.ListBuffer
 
 import org.apache.log4j.Level
+
 import org.apache.spark.util.{IntParam, MemoryParam, Utils}
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/deploy/FaultToleranceTest.scala b/core/src/main/scala/org/apache/spark/deploy/FaultToleranceTest.scala
index b4edb6109e..c0ede4b7c8 100644
--- a/core/src/main/scala/org/apache/spark/deploy/FaultToleranceTest.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/FaultToleranceTest.scala
@@ -22,7 +22,7 @@ import java.net.URL
 import java.util.concurrent.TimeoutException
 
 import scala.collection.mutable.ListBuffer
-import scala.concurrent.{Await, future, promise}
+import scala.concurrent.{future, promise, Await}
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.duration._
 import scala.language.postfixOps
diff --git a/core/src/main/scala/org/apache/spark/deploy/LocalSparkCluster.scala b/core/src/main/scala/org/apache/spark/deploy/LocalSparkCluster.scala
index 5bb62d37d6..2dfb813d5f 100644
--- a/core/src/main/scala/org/apache/spark/deploy/LocalSparkCluster.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/LocalSparkCluster.scala
@@ -19,10 +19,10 @@ package org.apache.spark.deploy
 
 import scala.collection.mutable.ArrayBuffer
 
-import org.apache.spark.rpc.RpcEnv
 import org.apache.spark.{Logging, SparkConf}
-import org.apache.spark.deploy.worker.Worker
 import org.apache.spark.deploy.master.Master
+import org.apache.spark.deploy.worker.Worker
+import org.apache.spark.rpc.RpcEnv
 import org.apache.spark.util.Utils
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala b/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala
index d85327603f..c0a9e3f280 100644
--- a/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.deploy
 
-import java.net.URI
 import java.io.File
+import java.net.URI
 
 import scala.collection.mutable.ArrayBuffer
 import scala.collection.JavaConverters._
diff --git a/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala b/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala
index d46dc87a92..4911c3be3a 100644
--- a/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala
@@ -26,7 +26,7 @@ import scala.collection.JavaConverters._
 
 import com.google.common.io.{ByteStreams, Files}
 
-import org.apache.spark.{SparkException, Logging}
+import org.apache.spark.{Logging, SparkException}
 import org.apache.spark.api.r.RUtils
 import org.apache.spark.util.{RedirectThread, Utils}
 
diff --git a/core/src/main/scala/org/apache/spark/deploy/RRunner.scala b/core/src/main/scala/org/apache/spark/deploy/RRunner.scala
index 661f7317c6..d0466830b2 100644
--- a/core/src/main/scala/org/apache/spark/deploy/RRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/RRunner.scala
@@ -24,8 +24,8 @@ import scala.collection.JavaConverters._
 
 import org.apache.hadoop.fs.Path
 
-import org.apache.spark.api.r.{RBackend, RUtils}
 import org.apache.spark.{SparkException, SparkUserAppException}
+import org.apache.spark.api.r.{RBackend, RUtils}
 import org.apache.spark.util.RedirectThread
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala b/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
index 4bd94f13e5..8ba3f5e241 100644
--- a/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
@@ -29,15 +29,15 @@ import scala.util.control.NonFatal
 
 import com.google.common.primitives.Longs
 import org.apache.hadoop.conf.Configuration
-import org.apache.hadoop.fs.FileSystem.Statistics
 import org.apache.hadoop.fs.{FileStatus, FileSystem, Path, PathFilter}
+import org.apache.hadoop.fs.FileSystem.Statistics
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier
 import org.apache.hadoop.mapred.JobConf
 import org.apache.hadoop.security.{Credentials, UserGroupInformation}
 
+import org.apache.spark.{Logging, SparkConf, SparkException}
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.util.Utils
-import org.apache.spark.{Logging, SparkConf, SparkException}
 
 /**
  * :: DeveloperApi ::
diff --git a/core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala b/core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala
index 669b6b614e..a1e8da1ec8 100644
--- a/core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala
@@ -37,9 +37,9 @@ import org.apache.ivy.core.retrieve.RetrieveOptions
 import org.apache.ivy.core.settings.IvySettings
 import org.apache.ivy.plugins.matcher.GlobPatternMatcher
 import org.apache.ivy.plugins.repository.file.FileRepository
-import org.apache.ivy.plugins.resolver.{FileSystemResolver, ChainResolver, IBiblioResolver}
+import org.apache.ivy.plugins.resolver.{ChainResolver, FileSystemResolver, IBiblioResolver}
 
-import org.apache.spark.{SparkException, SparkUserAppException, SPARK_VERSION}
+import org.apache.spark.{SPARK_VERSION, SparkException, SparkUserAppException}
 import org.apache.spark.api.r.RUtils
 import org.apache.spark.deploy.rest._
 import org.apache.spark.util.{ChildFirstURLClassLoader, MutableURLClassLoader, Utils}
diff --git a/core/src/main/scala/org/apache/spark/deploy/client/AppClient.scala b/core/src/main/scala/org/apache/spark/deploy/client/AppClient.scala
index f7c33214c2..a7a0a78f14 100644
--- a/core/src/main/scala/org/apache/spark/deploy/client/AppClient.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/client/AppClient.scala
@@ -18,8 +18,8 @@
 package org.apache.spark.deploy.client
 
 import java.util.concurrent._
-import java.util.concurrent.atomic.{AtomicBoolean, AtomicReference}
 import java.util.concurrent.{Future => JFuture, ScheduledFuture => JScheduledFuture}
+import java.util.concurrent.atomic.{AtomicBoolean, AtomicReference}
 
 import scala.util.control.NonFatal
 
diff --git a/core/src/main/scala/org/apache/spark/deploy/client/TestClient.scala b/core/src/main/scala/org/apache/spark/deploy/client/TestClient.scala
index adb3f02258..f8d3da24b9 100644
--- a/core/src/main/scala/org/apache/spark/deploy/client/TestClient.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/client/TestClient.scala
@@ -17,9 +17,9 @@
 
 package org.apache.spark.deploy.client
 
-import org.apache.spark.rpc.RpcEnv
-import org.apache.spark.{SecurityManager, SparkConf, Logging}
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.{ApplicationDescription, Command}
+import org.apache.spark.rpc.RpcEnv
 import org.apache.spark.util.Utils
 
 private[spark] object TestClient {
diff --git a/core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala b/core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala
index c93bc8c127..22e4155cc5 100644
--- a/core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala
@@ -19,7 +19,7 @@ package org.apache.spark.deploy.history
 
 import java.io.{BufferedInputStream, FileNotFoundException, InputStream, IOException, OutputStream}
 import java.util.UUID
-import java.util.concurrent.{ExecutorService, Executors, TimeUnit}
+import java.util.concurrent.{Executors, ExecutorService, TimeUnit}
 import java.util.zip.{ZipEntry, ZipOutputStream}
 
 import scala.collection.mutable
diff --git a/core/src/main/scala/org/apache/spark/deploy/history/HistoryPage.scala b/core/src/main/scala/org/apache/spark/deploy/history/HistoryPage.scala
index 642d71b18c..04bad79dcc 100644
--- a/core/src/main/scala/org/apache/spark/deploy/history/HistoryPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/history/HistoryPage.scala
@@ -21,7 +21,7 @@ import javax.servlet.http.HttpServletRequest
 
 import scala.xml.Node
 
-import org.apache.spark.ui.{WebUIPage, UIUtils}
+import org.apache.spark.ui.{UIUtils, WebUIPage}
 
 private[history] class HistoryPage(parent: HistoryServer) extends WebUIPage("") {
 
diff --git a/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala b/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala
index 6143a33b69..96007a06e3 100644
--- a/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala
@@ -25,6 +25,7 @@ import scala.util.control.NonFatal
 
 import com.google.common.cache._
 import org.eclipse.jetty.servlet.{ServletContextHandler, ServletHolder}
+
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationInfo, ApplicationsListResource, UIRoot}
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/Master.scala b/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
index bd3d981ce0..0deab8ddd5 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
@@ -24,14 +24,13 @@ import java.util.Date
 import java.util.concurrent.{ConcurrentHashMap, ScheduledFuture, TimeUnit}
 
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
-import scala.concurrent.duration.Duration
 import scala.concurrent.{Await, ExecutionContext, Future}
+import scala.concurrent.duration.Duration
 import scala.language.postfixOps
 import scala.util.Random
 
 import org.apache.hadoop.fs.Path
 
-import org.apache.spark.rpc._
 import org.apache.spark.{Logging, SecurityManager, SparkConf, SparkException}
 import org.apache.spark.deploy.{ApplicationDescription, DriverDescription,
   ExecutorState, SparkHadoopUtil}
@@ -42,6 +41,7 @@ import org.apache.spark.deploy.master.MasterMessages._
 import org.apache.spark.deploy.master.ui.MasterWebUI
 import org.apache.spark.deploy.rest.StandaloneRestServer
 import org.apache.spark.metrics.MetricsSystem
+import org.apache.spark.rpc._
 import org.apache.spark.scheduler.{EventLoggingListener, ReplayListenerBus}
 import org.apache.spark.serializer.{JavaSerializer, Serializer}
 import org.apache.spark.ui.SparkUI
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/PersistenceEngine.scala b/core/src/main/scala/org/apache/spark/deploy/master/PersistenceEngine.scala
index 58a00bceee..dddf2be57e 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/PersistenceEngine.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/PersistenceEngine.scala
@@ -17,11 +17,11 @@
 
 package org.apache.spark.deploy.master
 
+import scala.reflect.ClassTag
+
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.rpc.RpcEnv
 
-import scala.reflect.ClassTag
-
 /**
  * Allows Master to persist any state that is necessary in order to recover from a failure.
  * The following semantics are required:
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperLeaderElectionAgent.scala b/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperLeaderElectionAgent.scala
index d317206a61..336cb24c19 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperLeaderElectionAgent.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperLeaderElectionAgent.scala
@@ -17,9 +17,10 @@
 
 package org.apache.spark.deploy.master
 
-import org.apache.spark.{Logging, SparkConf}
 import org.apache.curator.framework.CuratorFramework
-import org.apache.curator.framework.recipes.leader.{LeaderLatchListener, LeaderLatch}
+import org.apache.curator.framework.recipes.leader.{LeaderLatch, LeaderLatchListener}
+
+import org.apache.spark.{Logging, SparkConf}
 import org.apache.spark.deploy.SparkCuratorUtil
 
 private[master] class ZooKeeperLeaderElectionAgent(val masterInstance: LeaderElectable,
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/ui/ApplicationPage.scala b/core/src/main/scala/org/apache/spark/deploy/master/ui/ApplicationPage.scala
index f405aa2bdc..1b18cf0ded 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/ui/ApplicationPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/ui/ApplicationPage.scala
@@ -21,8 +21,8 @@ import javax.servlet.http.HttpServletRequest
 
 import scala.xml.Node
 
-import org.apache.spark.deploy.ExecutorState
 import org.apache.spark.deploy.DeployMessages.{MasterStateResponse, RequestMasterState}
+import org.apache.spark.deploy.ExecutorState
 import org.apache.spark.deploy.master.ExecutorDesc
 import org.apache.spark.ui.{UIUtils, WebUIPage}
 import org.apache.spark.util.Utils
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterPage.scala b/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterPage.scala
index ee539dd1f5..f9b0279c3d 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterPage.scala
@@ -23,10 +23,10 @@ import scala.xml.Node
 
 import org.json4s.JValue
 
+import org.apache.spark.deploy.DeployMessages.{KillDriverResponse, MasterStateResponse, RequestKillDriver, RequestMasterState}
 import org.apache.spark.deploy.JsonProtocol
-import org.apache.spark.deploy.DeployMessages.{KillDriverResponse, RequestKillDriver, MasterStateResponse, RequestMasterState}
 import org.apache.spark.deploy.master._
-import org.apache.spark.ui.{WebUIPage, UIUtils}
+import org.apache.spark.ui.{UIUtils, WebUIPage}
 import org.apache.spark.util.Utils
 
 private[ui] class MasterPage(parent: MasterWebUI) extends WebUIPage("") {
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterWebUI.scala b/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterWebUI.scala
index e41554a5a6..750ef0a962 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterWebUI.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/ui/MasterWebUI.scala
@@ -19,7 +19,7 @@ package org.apache.spark.deploy.master.ui
 
 import org.apache.spark.Logging
 import org.apache.spark.deploy.master.Master
-import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationsListResource, ApplicationInfo,
+import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationInfo, ApplicationsListResource,
   UIRoot}
 import org.apache.spark.ui.{SparkUI, WebUI}
 import org.apache.spark.ui.JettyUtils._
diff --git a/core/src/main/scala/org/apache/spark/deploy/mesos/MesosClusterDispatcher.scala b/core/src/main/scala/org/apache/spark/deploy/mesos/MesosClusterDispatcher.scala
index 89f1a8671f..66e1e64500 100644
--- a/core/src/main/scala/org/apache/spark/deploy/mesos/MesosClusterDispatcher.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/mesos/MesosClusterDispatcher.scala
@@ -19,11 +19,11 @@ package org.apache.spark.deploy.mesos
 
 import java.util.concurrent.CountDownLatch
 
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.mesos.ui.MesosClusterUI
 import org.apache.spark.deploy.rest.mesos.MesosRestServer
 import org.apache.spark.scheduler.cluster.mesos._
 import org.apache.spark.util.{ShutdownHookManager, Utils}
-import org.apache.spark.{Logging, SecurityManager, SparkConf}
 
 /*
  * A dispatcher that is responsible for managing and launching drivers, and is intended to be
diff --git a/core/src/main/scala/org/apache/spark/deploy/mesos/ui/DriverPage.scala b/core/src/main/scala/org/apache/spark/deploy/mesos/ui/DriverPage.scala
index bc67fd460d..807835105e 100644
--- a/core/src/main/scala/org/apache/spark/deploy/mesos/ui/DriverPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/mesos/ui/DriverPage.scala
@@ -23,10 +23,9 @@ import scala.xml.Node
 
 import org.apache.spark.deploy.Command
 import org.apache.spark.deploy.mesos.MesosDriverDescription
-import org.apache.spark.scheduler.cluster.mesos.{MesosClusterSubmissionState, MesosClusterRetryState}
+import org.apache.spark.scheduler.cluster.mesos.{MesosClusterRetryState, MesosClusterSubmissionState}
 import org.apache.spark.ui.{UIUtils, WebUIPage}
 
-
 private[ui] class DriverPage(parent: MesosClusterUI) extends WebUIPage("driver") {
 
   override def render(request: HttpServletRequest): Seq[Node] = {
diff --git a/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterPage.scala b/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterPage.scala
index 7419fa9699..166f666fbc 100644
--- a/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterPage.scala
@@ -22,6 +22,7 @@ import javax.servlet.http.HttpServletRequest
 import scala.xml.Node
 
 import org.apache.mesos.Protos.TaskStatus
+
 import org.apache.spark.deploy.mesos.MesosDriverDescription
 import org.apache.spark.scheduler.cluster.mesos.MesosClusterSubmissionState
 import org.apache.spark.ui.{UIUtils, WebUIPage}
diff --git a/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterUI.scala b/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterUI.scala
index 3f693545a0..da9740bb41 100644
--- a/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterUI.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/mesos/ui/MesosClusterUI.scala
@@ -17,10 +17,10 @@
 
 package org.apache.spark.deploy.mesos.ui
 
-import org.apache.spark.scheduler.cluster.mesos.MesosClusterScheduler
 import org.apache.spark.{SecurityManager, SparkConf}
-import org.apache.spark.ui.JettyUtils._
+import org.apache.spark.scheduler.cluster.mesos.MesosClusterScheduler
 import org.apache.spark.ui.{SparkUI, WebUI}
+import org.apache.spark.ui.JettyUtils._
 
 /**
  * UI that displays driver results from the [[org.apache.spark.deploy.mesos.MesosClusterDispatcher]]
diff --git a/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionClient.scala b/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionClient.scala
index 0744c64d5e..4ec6bfe2f9 100644
--- a/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionClient.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionClient.scala
@@ -23,15 +23,15 @@ import java.util.concurrent.TimeoutException
 import javax.servlet.http.HttpServletResponse
 
 import scala.collection.mutable
-import scala.concurrent.duration._
 import scala.concurrent.{Await, Future}
+import scala.concurrent.duration._
 import scala.io.Source
 
 import com.fasterxml.jackson.core.JsonProcessingException
 import com.google.common.base.Charsets
 
-import org.apache.spark.util.Utils
 import org.apache.spark.{Logging, SPARK_VERSION => sparkVersion, SparkConf}
+import org.apache.spark.util.Utils
 
 /**
  * A client that submits applications to a [[RestSubmissionServer]].
diff --git a/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionServer.scala b/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionServer.scala
index 2e78d03e5c..8e0862df4c 100644
--- a/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionServer.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/rest/RestSubmissionServer.scala
@@ -21,14 +21,15 @@ import java.net.InetSocketAddress
 import javax.servlet.http.{HttpServlet, HttpServletRequest, HttpServletResponse}
 
 import scala.io.Source
+
 import com.fasterxml.jackson.core.JsonProcessingException
 import org.eclipse.jetty.server.Server
-import org.eclipse.jetty.servlet.{ServletHolder, ServletContextHandler}
+import org.eclipse.jetty.servlet.{ServletContextHandler, ServletHolder}
 import org.eclipse.jetty.util.thread.QueuedThreadPool
 import org.json4s._
 import org.json4s.jackson.JsonMethods._
 
-import org.apache.spark.{Logging, SparkConf, SPARK_VERSION => sparkVersion}
+import org.apache.spark.{Logging, SPARK_VERSION => sparkVersion, SparkConf}
 import org.apache.spark.util.Utils
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/deploy/rest/StandaloneRestServer.scala b/core/src/main/scala/org/apache/spark/deploy/rest/StandaloneRestServer.scala
index d5b9bcab14..c19296c7b3 100644
--- a/core/src/main/scala/org/apache/spark/deploy/rest/StandaloneRestServer.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/rest/StandaloneRestServer.scala
@@ -20,11 +20,11 @@ package org.apache.spark.deploy.rest
 import java.io.File
 import javax.servlet.http.HttpServletResponse
 
-import org.apache.spark.deploy.ClientArguments._
+import org.apache.spark.{SPARK_VERSION => sparkVersion, SparkConf}
 import org.apache.spark.deploy.{Command, DeployMessages, DriverDescription}
+import org.apache.spark.deploy.ClientArguments._
 import org.apache.spark.rpc.RpcEndpointRef
 import org.apache.spark.util.Utils
-import org.apache.spark.{SPARK_VERSION => sparkVersion, SparkConf}
 
 /**
  * A server that responds to requests submitted by the [[RestSubmissionClient]].
diff --git a/core/src/main/scala/org/apache/spark/deploy/rest/mesos/MesosRestServer.scala b/core/src/main/scala/org/apache/spark/deploy/rest/mesos/MesosRestServer.scala
index 868cc35d06..a8b2f78889 100644
--- a/core/src/main/scala/org/apache/spark/deploy/rest/mesos/MesosRestServer.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/rest/mesos/MesosRestServer.scala
@@ -23,13 +23,12 @@ import java.util.Date
 import java.util.concurrent.atomic.AtomicLong
 import javax.servlet.http.HttpServletResponse
 
+import org.apache.spark.{SPARK_VERSION => sparkVersion, SparkConf}
 import org.apache.spark.deploy.Command
 import org.apache.spark.deploy.mesos.MesosDriverDescription
 import org.apache.spark.deploy.rest._
 import org.apache.spark.scheduler.cluster.mesos.MesosClusterScheduler
 import org.apache.spark.util.Utils
-import org.apache.spark.{SPARK_VERSION => sparkVersion, SparkConf}
-
 
 /**
  * A server that responds to requests submitted by the [[RestSubmissionClient]].
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala b/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala
index 89159ff5e2..6049db6d98 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala
@@ -25,13 +25,13 @@ import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
 import org.apache.hadoop.fs.Path
 
-import org.apache.spark.{Logging, SparkConf, SecurityManager}
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.{DriverDescription, SparkHadoopUtil}
 import org.apache.spark.deploy.DeployMessages.DriverStateChanged
 import org.apache.spark.deploy.master.DriverState
 import org.apache.spark.deploy.master.DriverState.DriverState
 import org.apache.spark.rpc.RpcEndpointRef
-import org.apache.spark.util.{Utils, Clock, SystemClock}
+import org.apache.spark.util.{Clock, SystemClock, Utils}
 
 /**
  * Manages the execution of one driver, including automatically restarting the driver on failure.
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala b/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala
index 9c4b8cdc64..c6687a4c63 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala
@@ -23,12 +23,13 @@ import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
-import org.apache.spark.deploy.DeployMessages.ExecutorStateChanged
+
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.{ApplicationDescription, ExecutorState}
+import org.apache.spark.deploy.DeployMessages.ExecutorStateChanged
 import org.apache.spark.rpc.RpcEndpointRef
 import org.apache.spark.util.{ShutdownHookManager, Utils}
 import org.apache.spark.util.logging.FileAppender
-import org.apache.spark.{Logging, SecurityManager, SparkConf}
 
 /**
  * Manages the execution of one executor process.
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala b/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
index 37b94e02cc..98e17da489 100755
--- a/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
@@ -20,7 +20,7 @@ package org.apache.spark.deploy.worker
 import java.io.File
 import java.io.IOException
 import java.text.SimpleDateFormat
-import java.util.{UUID, Date}
+import java.util.{Date, UUID}
 import java.util.concurrent._
 import java.util.concurrent.{Future => JFuture, ScheduledFuture => JScheduledFuture}
 
@@ -37,7 +37,7 @@ import org.apache.spark.deploy.master.{DriverState, Master}
 import org.apache.spark.deploy.worker.ui.WorkerWebUI
 import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.rpc._
-import org.apache.spark.util.{ThreadUtils, SignalLogger, Utils}
+import org.apache.spark.util.{SignalLogger, ThreadUtils, Utils}
 
 private[deploy] class Worker(
     override val rpcEnv: RpcEnv,
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/ui/LogPage.scala b/core/src/main/scala/org/apache/spark/deploy/worker/ui/LogPage.scala
index 5a1d06eb87..49803a27a5 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/ui/LogPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/ui/LogPage.scala
@@ -23,9 +23,9 @@ import javax.servlet.http.HttpServletRequest
 
 import scala.xml.Node
 
-import org.apache.spark.ui.{WebUIPage, UIUtils}
-import org.apache.spark.util.Utils
 import org.apache.spark.Logging
+import org.apache.spark.ui.{UIUtils, WebUIPage}
+import org.apache.spark.util.Utils
 import org.apache.spark.util.logging.RollingFileAppender
 
 private[ui] class LogPage(parent: WorkerWebUI) extends WebUIPage("logPage") with Logging {
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/ui/WorkerPage.scala b/core/src/main/scala/org/apache/spark/deploy/worker/ui/WorkerPage.scala
index fd905feb97..8ebcbcb6a1 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/ui/WorkerPage.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/ui/WorkerPage.scala
@@ -17,16 +17,17 @@
 
 package org.apache.spark.deploy.worker.ui
 
+import javax.servlet.http.HttpServletRequest
+
 import scala.xml.Node
 
-import javax.servlet.http.HttpServletRequest
 import org.json4s.JValue
 
-import org.apache.spark.deploy.JsonProtocol
 import org.apache.spark.deploy.DeployMessages.{RequestWorkerState, WorkerStateResponse}
+import org.apache.spark.deploy.JsonProtocol
 import org.apache.spark.deploy.master.DriverState
 import org.apache.spark.deploy.worker.{DriverRunner, ExecutorRunner}
-import org.apache.spark.ui.{WebUIPage, UIUtils}
+import org.apache.spark.ui.{UIUtils, WebUIPage}
 import org.apache.spark.util.Utils
 
 private[ui] class WorkerPage(parent: WorkerWebUI) extends WebUIPage("") {
diff --git a/core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala b/core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala
index edbd7225ca..58bd9ca3d1 100644
--- a/core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala
+++ b/core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala
@@ -22,11 +22,12 @@ import java.nio.ByteBuffer
 
 import scala.collection.mutable
 import scala.util.{Failure, Success}
-import org.apache.spark.rpc._
+
 import org.apache.spark._
 import org.apache.spark.TaskState.TaskState
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.deploy.worker.WorkerWatcher
+import org.apache.spark.rpc._
 import org.apache.spark.scheduler.TaskDescription
 import org.apache.spark.scheduler.cluster.CoarseGrainedClusterMessages._
 import org.apache.spark.serializer.SerializerInstance
diff --git a/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala b/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala
index d85465eb25..cfd9bcd65c 100644
--- a/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala
+++ b/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala
@@ -21,9 +21,9 @@ import java.nio.ByteBuffer
 
 import scala.collection.JavaConverters._
 
-import org.apache.mesos.protobuf.ByteString
 import org.apache.mesos.{Executor => MesosExecutor, ExecutorDriver, MesosExecutorDriver}
 import org.apache.mesos.Protos.{TaskStatus => MesosTaskStatus, _}
+import org.apache.mesos.protobuf.ByteString
 
 import org.apache.spark.{Logging, SparkConf, SparkEnv, TaskState}
 import org.apache.spark.TaskState.TaskState
diff --git a/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryInputFormat.scala b/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryInputFormat.scala
index 30431a9b98..bc98273add 100644
--- a/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryInputFormat.scala
+++ b/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryInputFormat.scala
@@ -19,8 +19,8 @@ package org.apache.spark.input
 
 import org.apache.hadoop.fs.Path
 import org.apache.hadoop.io.{BytesWritable, LongWritable}
-import org.apache.hadoop.mapreduce.lib.input.FileInputFormat
 import org.apache.hadoop.mapreduce.{InputSplit, JobContext, RecordReader, TaskAttemptContext}
+import org.apache.hadoop.mapreduce.lib.input.FileInputFormat
 
 import org.apache.spark.Logging
 
diff --git a/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryRecordReader.scala b/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryRecordReader.scala
index 25596a15d9..549395314b 100644
--- a/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryRecordReader.scala
+++ b/core/src/main/scala/org/apache/spark/input/FixedLengthBinaryRecordReader.scala
@@ -20,8 +20,8 @@ package org.apache.spark.input
 import java.io.IOException
 
 import org.apache.hadoop.fs.FSDataInputStream
-import org.apache.hadoop.io.compress.CompressionCodecFactory
 import org.apache.hadoop.io.{BytesWritable, LongWritable}
+import org.apache.hadoop.io.compress.CompressionCodecFactory
 import org.apache.hadoop.mapreduce.{InputSplit, RecordReader, TaskAttemptContext}
 import org.apache.hadoop.mapreduce.lib.input.FileSplit
 
diff --git a/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala b/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
index cb76e3c344..8009491a1b 100644
--- a/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
+++ b/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
@@ -21,7 +21,7 @@ import java.io.{ByteArrayInputStream, ByteArrayOutputStream, DataInputStream, Da
 
 import scala.collection.JavaConverters._
 
-import com.google.common.io.{Closeables, ByteStreams}
+import com.google.common.io.{ByteStreams, Closeables}
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.fs.Path
 import org.apache.hadoop.mapreduce.{InputSplit, JobContext, RecordReader, TaskAttemptContext}
diff --git a/core/src/main/scala/org/apache/spark/input/WholeTextFileRecordReader.scala b/core/src/main/scala/org/apache/spark/input/WholeTextFileRecordReader.scala
index 998c898a3f..6b7f086678 100644
--- a/core/src/main/scala/org/apache/spark/input/WholeTextFileRecordReader.scala
+++ b/core/src/main/scala/org/apache/spark/input/WholeTextFileRecordReader.scala
@@ -17,15 +17,14 @@
 
 package org.apache.spark.input
 
-import org.apache.hadoop.conf.{Configuration, Configurable => HConfigurable}
 import com.google.common.io.{ByteStreams, Closeables}
-
+import org.apache.hadoop.conf.{Configurable => HConfigurable, Configuration}
 import org.apache.hadoop.io.Text
 import org.apache.hadoop.io.compress.CompressionCodecFactory
 import org.apache.hadoop.mapreduce.InputSplit
-import org.apache.hadoop.mapreduce.lib.input.{CombineFileSplit, CombineFileRecordReader}
 import org.apache.hadoop.mapreduce.RecordReader
 import org.apache.hadoop.mapreduce.TaskAttemptContext
+import org.apache.hadoop.mapreduce.lib.input.{CombineFileRecordReader, CombineFileSplit}
 
 /**
  * A trait to implement [[org.apache.hadoop.conf.Configurable Configurable]] interface.
diff --git a/core/src/main/scala/org/apache/spark/mapred/SparkHadoopMapRedUtil.scala b/core/src/main/scala/org/apache/spark/mapred/SparkHadoopMapRedUtil.scala
index 249bdf5994..6841485f4b 100644
--- a/core/src/main/scala/org/apache/spark/mapred/SparkHadoopMapRedUtil.scala
+++ b/core/src/main/scala/org/apache/spark/mapred/SparkHadoopMapRedUtil.scala
@@ -22,8 +22,8 @@ import java.io.IOException
 import org.apache.hadoop.mapreduce.{TaskAttemptContext => MapReduceTaskAttemptContext}
 import org.apache.hadoop.mapreduce.{OutputCommitter => MapReduceOutputCommitter}
 
-import org.apache.spark.executor.CommitDeniedException
 import org.apache.spark.{Logging, SparkEnv, TaskContext}
+import org.apache.spark.executor.CommitDeniedException
 
 object SparkHadoopMapRedUtil extends Logging {
   /**
diff --git a/core/src/main/scala/org/apache/spark/memory/MemoryManager.scala b/core/src/main/scala/org/apache/spark/memory/MemoryManager.scala
index e707e27d96..33f8b9f16c 100644
--- a/core/src/main/scala/org/apache/spark/memory/MemoryManager.scala
+++ b/core/src/main/scala/org/apache/spark/memory/MemoryManager.scala
@@ -21,7 +21,7 @@ import javax.annotation.concurrent.GuardedBy
 
 import scala.collection.mutable
 
-import org.apache.spark.{SparkConf, Logging}
+import org.apache.spark.{Logging, SparkConf}
 import org.apache.spark.storage.{BlockId, BlockStatus, MemoryStore}
 import org.apache.spark.unsafe.array.ByteArrayMethods
 import org.apache.spark.unsafe.memory.MemoryAllocator
diff --git a/core/src/main/scala/org/apache/spark/memory/StorageMemoryPool.scala b/core/src/main/scala/org/apache/spark/memory/StorageMemoryPool.scala
index 70af83b5ee..4036484aad 100644
--- a/core/src/main/scala/org/apache/spark/memory/StorageMemoryPool.scala
+++ b/core/src/main/scala/org/apache/spark/memory/StorageMemoryPool.scala
@@ -22,8 +22,8 @@ import javax.annotation.concurrent.GuardedBy
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 
-import org.apache.spark.{TaskContext, Logging}
-import org.apache.spark.storage.{MemoryStore, BlockStatus, BlockId}
+import org.apache.spark.{Logging, TaskContext}
+import org.apache.spark.storage.{BlockId, BlockStatus, MemoryStore}
 
 /**
  * Performs bookkeeping for managing an adjustable-size pool of memory that is used for storage
diff --git a/core/src/main/scala/org/apache/spark/memory/UnifiedMemoryManager.scala b/core/src/main/scala/org/apache/spark/memory/UnifiedMemoryManager.scala
index 829f054dba..57a24ac140 100644
--- a/core/src/main/scala/org/apache/spark/memory/UnifiedMemoryManager.scala
+++ b/core/src/main/scala/org/apache/spark/memory/UnifiedMemoryManager.scala
@@ -20,7 +20,7 @@ package org.apache.spark.memory
 import scala.collection.mutable
 
 import org.apache.spark.SparkConf
-import org.apache.spark.storage.{BlockStatus, BlockId}
+import org.apache.spark.storage.{BlockId, BlockStatus}
 
 /**
  * A [[MemoryManager]] that enforces a soft boundary between execution and storage such that
diff --git a/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala b/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala
index dd2d325d87..8540984bfe 100644
--- a/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala
@@ -24,8 +24,8 @@ import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.util.matching.Regex
 
-import org.apache.spark.util.Utils
 import org.apache.spark.{Logging, SparkConf}
+import org.apache.spark.util.Utils
 
 private[spark] class MetricsConfig(conf: SparkConf) extends Logging {
 
diff --git a/core/src/main/scala/org/apache/spark/metrics/MetricsSystem.scala b/core/src/main/scala/org/apache/spark/metrics/MetricsSystem.scala
index fdf76d312d..e34cfc698d 100644
--- a/core/src/main/scala/org/apache/spark/metrics/MetricsSystem.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/MetricsSystem.scala
@@ -20,8 +20,6 @@ package org.apache.spark.metrics
 import java.util.Properties
 import java.util.concurrent.TimeUnit
 
-import org.apache.spark.util.Utils
-
 import scala.collection.mutable
 
 import com.codahale.metrics.{Metric, MetricFilter, MetricRegistry}
@@ -30,6 +28,7 @@ import org.eclipse.jetty.servlet.ServletContextHandler
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.metrics.sink.{MetricsServlet, Sink}
 import org.apache.spark.metrics.source.Source
+import org.apache.spark.util.Utils
 
 /**
  * Spark Metrics System, created by specific "instance", combined by source,
diff --git a/core/src/main/scala/org/apache/spark/metrics/sink/GraphiteSink.scala b/core/src/main/scala/org/apache/spark/metrics/sink/GraphiteSink.scala
index 2d25ebd661..22454e50b1 100644
--- a/core/src/main/scala/org/apache/spark/metrics/sink/GraphiteSink.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/sink/GraphiteSink.scala
@@ -22,7 +22,7 @@ import java.util.Properties
 import java.util.concurrent.TimeUnit
 
 import com.codahale.metrics.MetricRegistry
-import com.codahale.metrics.graphite.{GraphiteUDP, Graphite, GraphiteReporter}
+import com.codahale.metrics.graphite.{Graphite, GraphiteReporter, GraphiteUDP}
 
 import org.apache.spark.SecurityManager
 import org.apache.spark.metrics.MetricsSystem
diff --git a/core/src/main/scala/org/apache/spark/metrics/sink/JmxSink.scala b/core/src/main/scala/org/apache/spark/metrics/sink/JmxSink.scala
index 2588fe2c9e..1992b42ac7 100644
--- a/core/src/main/scala/org/apache/spark/metrics/sink/JmxSink.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/sink/JmxSink.scala
@@ -20,6 +20,7 @@ package org.apache.spark.metrics.sink
 import java.util.Properties
 
 import com.codahale.metrics.{JmxReporter, MetricRegistry}
+
 import org.apache.spark.SecurityManager
 
 private[spark] class JmxSink(val property: Properties, val registry: MetricRegistry,
diff --git a/core/src/main/scala/org/apache/spark/metrics/sink/MetricsServlet.scala b/core/src/main/scala/org/apache/spark/metrics/sink/MetricsServlet.scala
index 4193e1d21d..68b58b8490 100644
--- a/core/src/main/scala/org/apache/spark/metrics/sink/MetricsServlet.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/sink/MetricsServlet.scala
@@ -19,7 +19,6 @@ package org.apache.spark.metrics.sink
 
 import java.util.Properties
 import java.util.concurrent.TimeUnit
-
 import javax.servlet.http.HttpServletRequest
 
 import com.codahale.metrics.MetricRegistry
@@ -27,7 +26,7 @@ import com.codahale.metrics.json.MetricsModule
 import com.fasterxml.jackson.databind.ObjectMapper
 import org.eclipse.jetty.servlet.ServletContextHandler
 
-import org.apache.spark.{SparkConf, SecurityManager}
+import org.apache.spark.{SecurityManager, SparkConf}
 import org.apache.spark.ui.JettyUtils._
 
 private[spark] class MetricsServlet(
diff --git a/core/src/main/scala/org/apache/spark/metrics/sink/Slf4jSink.scala b/core/src/main/scala/org/apache/spark/metrics/sink/Slf4jSink.scala
index 11dfcfe2f0..773e074336 100644
--- a/core/src/main/scala/org/apache/spark/metrics/sink/Slf4jSink.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/sink/Slf4jSink.scala
@@ -20,7 +20,7 @@ package org.apache.spark.metrics.sink
 import java.util.Properties
 import java.util.concurrent.TimeUnit
 
-import com.codahale.metrics.{Slf4jReporter, MetricRegistry}
+import com.codahale.metrics.{MetricRegistry, Slf4jReporter}
 
 import org.apache.spark.SecurityManager
 import org.apache.spark.metrics.MetricsSystem
diff --git a/core/src/main/scala/org/apache/spark/network/BlockTransferService.scala b/core/src/main/scala/org/apache/spark/network/BlockTransferService.scala
index dcbda5a851..15d3540f34 100644
--- a/core/src/main/scala/org/apache/spark/network/BlockTransferService.scala
+++ b/core/src/main/scala/org/apache/spark/network/BlockTransferService.scala
@@ -20,13 +20,13 @@ package org.apache.spark.network
 import java.io.Closeable
 import java.nio.ByteBuffer
 
-import scala.concurrent.{Promise, Await, Future}
+import scala.concurrent.{Await, Future, Promise}
 import scala.concurrent.duration.Duration
 
 import org.apache.spark.Logging
-import org.apache.spark.network.buffer.{NioManagedBuffer, ManagedBuffer}
-import org.apache.spark.network.shuffle.{ShuffleClient, BlockFetchingListener}
-import org.apache.spark.storage.{BlockManagerId, BlockId, StorageLevel}
+import org.apache.spark.network.buffer.{ManagedBuffer, NioManagedBuffer}
+import org.apache.spark.network.shuffle.{BlockFetchingListener, ShuffleClient}
+import org.apache.spark.storage.{BlockId, BlockManagerId, StorageLevel}
 
 private[spark]
 abstract class BlockTransferService extends ShuffleClient with Closeable with Logging {
diff --git a/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala b/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala
index 40604a4da1..f588a28eed 100644
--- a/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala
+++ b/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala
@@ -25,10 +25,10 @@ import scala.concurrent.{Future, Promise}
 import org.apache.spark.{SecurityManager, SparkConf}
 import org.apache.spark.network._
 import org.apache.spark.network.buffer.ManagedBuffer
-import org.apache.spark.network.client.{TransportClientBootstrap, RpcResponseCallback, TransportClientFactory}
+import org.apache.spark.network.client.{RpcResponseCallback, TransportClientBootstrap, TransportClientFactory}
 import org.apache.spark.network.sasl.{SaslClientBootstrap, SaslServerBootstrap}
 import org.apache.spark.network.server._
-import org.apache.spark.network.shuffle.{RetryingBlockFetcher, BlockFetchingListener, OneForOneBlockFetcher}
+import org.apache.spark.network.shuffle.{BlockFetchingListener, OneForOneBlockFetcher, RetryingBlockFetcher}
 import org.apache.spark.network.shuffle.protocol.UploadBlock
 import org.apache.spark.network.util.JavaUtils
 import org.apache.spark.serializer.JavaSerializer
diff --git a/core/src/main/scala/org/apache/spark/network/netty/SparkTransportConf.scala b/core/src/main/scala/org/apache/spark/network/netty/SparkTransportConf.scala
index 84833f59d7..86874e2067 100644
--- a/core/src/main/scala/org/apache/spark/network/netty/SparkTransportConf.scala
+++ b/core/src/main/scala/org/apache/spark/network/netty/SparkTransportConf.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.network.netty
 
 import org.apache.spark.SparkConf
-import org.apache.spark.network.util.{TransportConf, ConfigProvider}
+import org.apache.spark.network.util.{ConfigProvider, TransportConf}
 
 /**
  * Provides a utility for transforming from a SparkConf inside a Spark JVM (e.g., Executor,
diff --git a/core/src/main/scala/org/apache/spark/partial/StudentTCacher.scala b/core/src/main/scala/org/apache/spark/partial/StudentTCacher.scala
index 828bf96c2c..55acb9ca64 100644
--- a/core/src/main/scala/org/apache/spark/partial/StudentTCacher.scala
+++ b/core/src/main/scala/org/apache/spark/partial/StudentTCacher.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.partial
 
-import org.apache.commons.math3.distribution.{TDistribution, NormalDistribution}
+import org.apache.commons.math3.distribution.{NormalDistribution, TDistribution}
 
 /**
  * A utility class for caching Student's T distribution values for a given confidence level
diff --git a/core/src/main/scala/org/apache/spark/partial/SumEvaluator.scala b/core/src/main/scala/org/apache/spark/partial/SumEvaluator.scala
index 1753c2561b..44295e5a1a 100644
--- a/core/src/main/scala/org/apache/spark/partial/SumEvaluator.scala
+++ b/core/src/main/scala/org/apache/spark/partial/SumEvaluator.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.partial
 
-import org.apache.commons.math3.distribution.{TDistribution, NormalDistribution}
+import org.apache.commons.math3.distribution.{NormalDistribution, TDistribution}
 
 import org.apache.spark.util.StatCounter
 
diff --git a/core/src/main/scala/org/apache/spark/rdd/AsyncRDDActions.scala b/core/src/main/scala/org/apache/spark/rdd/AsyncRDDActions.scala
index 14f541f937..ec48925823 100644
--- a/core/src/main/scala/org/apache/spark/rdd/AsyncRDDActions.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/AsyncRDDActions.scala
@@ -20,10 +20,10 @@ package org.apache.spark.rdd
 import java.util.concurrent.atomic.AtomicLong
 
 import scala.collection.mutable.ArrayBuffer
-import scala.concurrent.{Future, ExecutionContext}
+import scala.concurrent.{ExecutionContext, Future}
 import scala.reflect.ClassTag
 
-import org.apache.spark.{JobSubmitter, ComplexFutureAction, FutureAction, Logging}
+import org.apache.spark.{ComplexFutureAction, FutureAction, JobSubmitter, Logging}
 import org.apache.spark.util.ThreadUtils
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/rdd/BinaryFileRDD.scala b/core/src/main/scala/org/apache/spark/rdd/BinaryFileRDD.scala
index 2bf2337d49..be0cb175f5 100644
--- a/core/src/main/scala/org/apache/spark/rdd/BinaryFileRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/BinaryFileRDD.scala
@@ -22,8 +22,8 @@ import org.apache.hadoop.io.Writable
 import org.apache.hadoop.mapreduce._
 import org.apache.hadoop.mapreduce.task.JobContextImpl
 
+import org.apache.spark.{Partition, SparkContext}
 import org.apache.spark.input.StreamFileInputFormat
-import org.apache.spark.{ Partition, SparkContext }
 
 private[spark] class BinaryFileRDD[T](
     sc: SparkContext,
diff --git a/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala b/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala
index fc1710fbad..8358244987 100644
--- a/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala
@@ -21,7 +21,6 @@ import scala.reflect.ClassTag
 
 import org.apache.spark._
 import org.apache.spark.storage.{BlockId, BlockManager}
-import scala.Some
 
 private[spark] class BlockRDDPartition(val blockId: BlockId, idx: Int) extends Partition {
   val index = idx
diff --git a/core/src/main/scala/org/apache/spark/rdd/CoGroupedRDD.scala b/core/src/main/scala/org/apache/spark/rdd/CoGroupedRDD.scala
index 3a0ca1d813..3587e7eb1a 100644
--- a/core/src/main/scala/org/apache/spark/rdd/CoGroupedRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/CoGroupedRDD.scala
@@ -17,18 +17,17 @@
 
 package org.apache.spark.rdd
 
-import scala.language.existentials
-
 import java.io.{IOException, ObjectOutputStream}
 
 import scala.collection.mutable.ArrayBuffer
+import scala.language.existentials
 import scala.reflect.ClassTag
 
 import org.apache.spark._
 import org.apache.spark.annotation.DeveloperApi
+import org.apache.spark.serializer.Serializer
 import org.apache.spark.util.collection.{CompactBuffer, ExternalAppendOnlyMap}
 import org.apache.spark.util.Utils
-import org.apache.spark.serializer.Serializer
 
 /** The references to rdd and splitIndex are transient because redundant information is stored
   * in the CoGroupedRDD object.  Because CoGroupedRDD is serialized separately from
diff --git a/core/src/main/scala/org/apache/spark/rdd/DoubleRDDFunctions.scala b/core/src/main/scala/org/apache/spark/rdd/DoubleRDDFunctions.scala
index 7fbaadcea3..c07f346bba 100644
--- a/core/src/main/scala/org/apache/spark/rdd/DoubleRDDFunctions.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/DoubleRDDFunctions.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.rdd
 
+import org.apache.spark.{Logging, TaskContext}
 import org.apache.spark.annotation.Experimental
-import org.apache.spark.{TaskContext, Logging}
 import org.apache.spark.partial.BoundedDouble
 import org.apache.spark.partial.MeanEvaluator
 import org.apache.spark.partial.PartialResult
diff --git a/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala b/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
index 920d3bf219..a7a6e0b8a9 100644
--- a/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
@@ -17,22 +17,22 @@
 
 package org.apache.spark.rdd
 
+import java.io.EOFException
 import java.text.SimpleDateFormat
 import java.util.Date
-import java.io.EOFException
 
 import scala.collection.immutable.Map
-import scala.reflect.ClassTag
 import scala.collection.mutable.ListBuffer
+import scala.reflect.ClassTag
 
 import org.apache.hadoop.conf.{Configurable, Configuration}
 import org.apache.hadoop.mapred.FileSplit
 import org.apache.hadoop.mapred.InputFormat
 import org.apache.hadoop.mapred.InputSplit
 import org.apache.hadoop.mapred.JobConf
+import org.apache.hadoop.mapred.JobID
 import org.apache.hadoop.mapred.RecordReader
 import org.apache.hadoop.mapred.Reporter
-import org.apache.hadoop.mapred.JobID
 import org.apache.hadoop.mapred.TaskAttemptID
 import org.apache.hadoop.mapred.TaskID
 import org.apache.hadoop.mapred.lib.CombineFileSplit
@@ -45,9 +45,9 @@ import org.apache.spark.broadcast.Broadcast
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.executor.DataReadMethod
 import org.apache.spark.rdd.HadoopRDD.HadoopMapPartitionsWithSplitRDD
-import org.apache.spark.util.{SerializableConfiguration, ShutdownHookManager, NextIterator, Utils}
-import org.apache.spark.scheduler.{HostTaskLocation, HDFSCacheTaskLocation}
+import org.apache.spark.scheduler.{HDFSCacheTaskLocation, HostTaskLocation}
 import org.apache.spark.storage.StorageLevel
+import org.apache.spark.util.{NextIterator, SerializableConfiguration, ShutdownHookManager, Utils}
 
 /**
  * A Spark split class that wraps around a Hadoop InputSplit.
diff --git a/core/src/main/scala/org/apache/spark/rdd/JdbcRDD.scala b/core/src/main/scala/org/apache/spark/rdd/JdbcRDD.scala
index 0c28f045e4..469962db67 100644
--- a/core/src/main/scala/org/apache/spark/rdd/JdbcRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/JdbcRDD.scala
@@ -17,15 +17,15 @@
 
 package org.apache.spark.rdd
 
-import java.sql.{PreparedStatement, Connection, ResultSet}
+import java.sql.{Connection, PreparedStatement, ResultSet}
 
 import scala.reflect.ClassTag
 
+import org.apache.spark.{Logging, Partition, SparkContext, TaskContext}
+import org.apache.spark.api.java.{JavaRDD, JavaSparkContext}
 import org.apache.spark.api.java.JavaSparkContext.fakeClassTag
 import org.apache.spark.api.java.function.{Function => JFunction}
-import org.apache.spark.api.java.{JavaRDD, JavaSparkContext}
 import org.apache.spark.util.NextIterator
-import org.apache.spark.{Logging, Partition, SparkContext, TaskContext}
 
 private[spark] class JdbcPartition(idx: Int, val lower: Long, val upper: Long) extends Partition {
   override def index: Int = idx
diff --git a/core/src/main/scala/org/apache/spark/rdd/NewHadoopRDD.scala b/core/src/main/scala/org/apache/spark/rdd/NewHadoopRDD.scala
index 8b330a34c3..146609ae39 100644
--- a/core/src/main/scala/org/apache/spark/rdd/NewHadoopRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/NewHadoopRDD.scala
@@ -28,13 +28,13 @@ import org.apache.hadoop.mapreduce._
 import org.apache.hadoop.mapreduce.lib.input.{CombineFileSplit, FileSplit}
 import org.apache.hadoop.mapreduce.task.{JobContextImpl, TaskAttemptContextImpl}
 
-import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark._
+import org.apache.spark.annotation.DeveloperApi
+import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.executor.DataReadMethod
 import org.apache.spark.rdd.NewHadoopRDD.NewHadoopMapPartitionsWithSplitRDD
-import org.apache.spark.util.{SerializableConfiguration, ShutdownHookManager}
-import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.storage.StorageLevel
+import org.apache.spark.util.{SerializableConfiguration, ShutdownHookManager}
 
 private[spark] class NewHadoopPartition(
     rddId: Int,
diff --git a/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala b/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
index 76b31165aa..16a856f594 100644
--- a/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
@@ -21,7 +21,7 @@ import java.nio.ByteBuffer
 import java.text.SimpleDateFormat
 import java.util.{Date, HashMap => JHashMap}
 
-import scala.collection.{Map, mutable}
+import scala.collection.{mutable, Map}
 import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.reflect.ClassTag
@@ -33,7 +33,7 @@ import org.apache.hadoop.fs.FileSystem
 import org.apache.hadoop.io.SequenceFile.CompressionType
 import org.apache.hadoop.io.compress.CompressionCodec
 import org.apache.hadoop.mapred.{FileOutputCommitter, FileOutputFormat, JobConf, OutputFormat}
-import org.apache.hadoop.mapreduce.{Job => NewAPIHadoopJob, OutputFormat => NewOutputFormat, RecordWriter => NewRecordWriter, TaskType, TaskAttemptID}
+import org.apache.hadoop.mapreduce.{Job => NewAPIHadoopJob, OutputFormat => NewOutputFormat, RecordWriter => NewRecordWriter, TaskAttemptID, TaskType}
 import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl
 
 import org.apache.spark._
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 394f79dc77..d6eac7888d 100644
--- a/core/src/main/scala/org/apache/spark/rdd/RDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/RDD.scala
@@ -31,7 +31,7 @@ import org.apache.hadoop.mapred.TextOutputFormat
 
 import org.apache.spark._
 import org.apache.spark.Partitioner._
-import org.apache.spark.annotation.{Since, DeveloperApi}
+import org.apache.spark.annotation.{DeveloperApi, Since}
 import org.apache.spark.api.java.JavaRDD
 import org.apache.spark.partial.BoundedDouble
 import org.apache.spark.partial.CountEvaluator
@@ -40,7 +40,7 @@ import org.apache.spark.partial.PartialResult
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.util.{BoundedPriorityQueue, Utils}
 import org.apache.spark.util.collection.OpenHashMap
-import org.apache.spark.util.random.{BernoulliSampler, PoissonSampler, BernoulliCellSampler,
+import org.apache.spark.util.random.{BernoulliCellSampler, BernoulliSampler, PoissonSampler,
   SamplingUtils}
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/rdd/SequenceFileRDDFunctions.scala b/core/src/main/scala/org/apache/spark/rdd/SequenceFileRDDFunctions.scala
index c4bc85a5ea..92d9e3581e 100644
--- a/core/src/main/scala/org/apache/spark/rdd/SequenceFileRDDFunctions.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/SequenceFileRDDFunctions.scala
@@ -16,7 +16,7 @@
  */
 package org.apache.spark.rdd
 
-import scala.reflect.{ClassTag, classTag}
+import scala.reflect.{classTag, ClassTag}
 
 import org.apache.hadoop.io.Writable
 import org.apache.hadoop.io.compress.CompressionCodec
diff --git a/core/src/main/scala/org/apache/spark/rpc/RpcEndpointRef.scala b/core/src/main/scala/org/apache/spark/rpc/RpcEndpointRef.scala
index 623da3e9c1..154398b572 100644
--- a/core/src/main/scala/org/apache/spark/rpc/RpcEndpointRef.scala
+++ b/core/src/main/scala/org/apache/spark/rpc/RpcEndpointRef.scala
@@ -20,8 +20,8 @@ package org.apache.spark.rpc
 import scala.concurrent.Future
 import scala.reflect.ClassTag
 
+import org.apache.spark.{Logging, SparkConf, SparkException}
 import org.apache.spark.util.RpcUtils
-import org.apache.spark.{SparkException, Logging, SparkConf}
 
 /**
  * A reference for a remote [[RpcEndpoint]]. [[RpcEndpointRef]] is thread-safe.
diff --git a/core/src/main/scala/org/apache/spark/rpc/RpcTimeout.scala b/core/src/main/scala/org/apache/spark/rpc/RpcTimeout.scala
index 285786ebf9..8b4ebf34ba 100644
--- a/core/src/main/scala/org/apache/spark/rpc/RpcTimeout.scala
+++ b/core/src/main/scala/org/apache/spark/rpc/RpcTimeout.scala
@@ -19,13 +19,12 @@ package org.apache.spark.rpc
 
 import java.util.concurrent.TimeoutException
 
-import scala.concurrent.{Awaitable, Await}
+import scala.concurrent.{Await, Awaitable}
 import scala.concurrent.duration._
 
 import org.apache.spark.SparkConf
 import org.apache.spark.util.Utils
 
-
 /**
  * An exception thrown if RpcTimeout modifies a [[TimeoutException]].
  */
diff --git a/core/src/main/scala/org/apache/spark/rpc/netty/Dispatcher.scala b/core/src/main/scala/org/apache/spark/rpc/netty/Dispatcher.scala
index 533c984766..19259e0e80 100644
--- a/core/src/main/scala/org/apache/spark/rpc/netty/Dispatcher.scala
+++ b/core/src/main/scala/org/apache/spark/rpc/netty/Dispatcher.scala
@@ -17,14 +17,14 @@
 
 package org.apache.spark.rpc.netty
 
-import java.util.concurrent.{ThreadPoolExecutor, ConcurrentHashMap, LinkedBlockingQueue, TimeUnit}
+import java.util.concurrent.{ConcurrentHashMap, LinkedBlockingQueue, ThreadPoolExecutor, TimeUnit}
 import javax.annotation.concurrent.GuardedBy
 
 import scala.collection.JavaConverters._
 import scala.concurrent.Promise
 import scala.util.control.NonFatal
 
-import org.apache.spark.{SparkException, Logging}
+import org.apache.spark.{Logging, SparkException}
 import org.apache.spark.network.client.RpcResponseCallback
 import org.apache.spark.rpc._
 import org.apache.spark.util.ThreadUtils
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 b128ed50ca..92438ba892 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala
@@ -40,8 +40,8 @@ import org.apache.spark.partial.{ApproximateActionListener, ApproximateEvaluator
 import org.apache.spark.rdd.RDD
 import org.apache.spark.rpc.RpcTimeout
 import org.apache.spark.storage._
-import org.apache.spark.util._
 import org.apache.spark.storage.BlockManagerMessages.BlockManagerHeartbeat
+import org.apache.spark.util._
 
 /**
  * The high-level scheduling layer that implements stage-oriented scheduling. It computes a DAG of
diff --git a/core/src/main/scala/org/apache/spark/scheduler/EventLoggingListener.scala b/core/src/main/scala/org/apache/spark/scheduler/EventLoggingListener.scala
index 68792c58c9..aa607c5a2d 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/EventLoggingListener.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/EventLoggingListener.scala
@@ -30,7 +30,7 @@ import org.apache.hadoop.fs.permission.FsPermission
 import org.json4s.JsonAST.JValue
 import org.json4s.jackson.JsonMethods._
 
-import org.apache.spark.{Logging, SparkConf, SPARK_VERSION}
+import org.apache.spark.{Logging, SPARK_VERSION, SparkConf}
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.io.CompressionCodec
 import org.apache.spark.util.{JsonProtocol, Utils}
diff --git a/core/src/main/scala/org/apache/spark/scheduler/OutputCommitCoordinator.scala b/core/src/main/scala/org/apache/spark/scheduler/OutputCommitCoordinator.scala
index 4d14667817..3e3ab15d8a 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/OutputCommitCoordinator.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/OutputCommitCoordinator.scala
@@ -20,7 +20,7 @@ package org.apache.spark.scheduler
 import scala.collection.mutable
 
 import org.apache.spark._
-import org.apache.spark.rpc.{RpcCallContext, RpcEndpointRef, RpcEnv, RpcEndpoint}
+import org.apache.spark.rpc.{RpcCallContext, RpcEndpoint, RpcEndpointRef, RpcEnv}
 
 private sealed trait OutputCommitCoordinationMessage extends Serializable
 
diff --git a/core/src/main/scala/org/apache/spark/scheduler/ResultTask.scala b/core/src/main/scala/org/apache/spark/scheduler/ResultTask.scala
index fb693721a9..6590cf6ffd 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/ResultTask.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/ResultTask.scala
@@ -17,9 +17,8 @@
 
 package org.apache.spark.scheduler
 
-import java.nio.ByteBuffer
-
 import java.io._
+import java.nio.ByteBuffer
 
 import org.apache.spark._
 import org.apache.spark.broadcast.Broadcast
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 075a7f1317..3130a65240 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/SparkListener.scala
@@ -29,8 +29,8 @@ import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.scheduler.cluster.ExecutorInfo
 import org.apache.spark.storage.{BlockManagerId, BlockUpdatedInfo}
-import org.apache.spark.util.{Distribution, Utils}
 import org.apache.spark.ui.SparkUI
+import org.apache.spark.util.{Distribution, Utils}
 
 @DeveloperApi
 @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "Event")
diff --git a/core/src/main/scala/org/apache/spark/scheduler/Task.scala b/core/src/main/scala/org/apache/spark/scheduler/Task.scala
index 9f27eed626..0379ca2af6 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/Task.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/Task.scala
@@ -22,14 +22,13 @@ import java.nio.ByteBuffer
 
 import scala.collection.mutable.HashMap
 
-import org.apache.spark.metrics.MetricsSystem
-import org.apache.spark.{Accumulator, SparkEnv, TaskContextImpl, TaskContext}
+import org.apache.spark.{Accumulator, SparkEnv, TaskContext, TaskContextImpl}
 import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.memory.TaskMemoryManager
+import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.serializer.SerializerInstance
 import org.apache.spark.util.{ByteBufferInputStream, ByteBufferOutputStream, Utils}
 
-
 /**
  * A unit of execution. We have two kinds of Task's in Spark:
  *
diff --git a/core/src/main/scala/org/apache/spark/scheduler/TaskScheduler.scala b/core/src/main/scala/org/apache/spark/scheduler/TaskScheduler.scala
index cb9a300810..7c0b007db7 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/TaskScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/TaskScheduler.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.scheduler
 
-import org.apache.spark.scheduler.SchedulingMode.SchedulingMode
 import org.apache.spark.executor.TaskMetrics
+import org.apache.spark.scheduler.SchedulingMode.SchedulingMode
 import org.apache.spark.storage.BlockManagerId
 
 /**
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 bdf19f9f27..6e3ef0e54f 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.scheduler
 
 import java.nio.ByteBuffer
-import java.util.{TimerTask, Timer}
+import java.util.{Timer, TimerTask}
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.AtomicLong
 
@@ -30,11 +30,11 @@ import scala.util.Random
 
 import org.apache.spark._
 import org.apache.spark.TaskState.TaskState
+import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.scheduler.SchedulingMode.SchedulingMode
 import org.apache.spark.scheduler.TaskLocality.TaskLocality
-import org.apache.spark.util.{ThreadUtils, Utils}
-import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.storage.BlockManagerId
+import org.apache.spark.util.{ThreadUtils, Utils}
 
 /**
  * Schedules tasks for multiple types of clusters by acting through a SchedulerBackend.
diff --git a/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala b/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
index 380301f1c9..aa39b59d8c 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
@@ -25,7 +25,7 @@ import java.util.concurrent.ConcurrentLinkedQueue
 import scala.collection.mutable.ArrayBuffer
 import scala.collection.mutable.HashMap
 import scala.collection.mutable.HashSet
-import scala.math.{min, max}
+import scala.math.{max, min}
 import scala.util.control.NonFatal
 
 import org.apache.spark._
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala
index f222007a38..b808993aa6 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala
@@ -22,12 +22,12 @@ import java.util.concurrent.atomic.AtomicInteger
 
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
 
-import org.apache.spark.rpc._
 import org.apache.spark.{ExecutorAllocationClient, Logging, SparkEnv, SparkException, TaskState}
+import org.apache.spark.rpc._
 import org.apache.spark.scheduler._
 import org.apache.spark.scheduler.cluster.CoarseGrainedClusterMessages._
 import org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend.ENDPOINT_NAME
-import org.apache.spark.util.{ThreadUtils, SerializableBuffer, AkkaUtils, Utils}
+import org.apache.spark.util.{AkkaUtils, SerializableBuffer, ThreadUtils, Utils}
 
 /**
  * A scheduler backend that waits for coarse-grained executors to connect.
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/ExecutorData.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/ExecutorData.scala
index 626a2b7d69..b25a4bfb50 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/ExecutorData.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/ExecutorData.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.scheduler.cluster
 
-import org.apache.spark.rpc.{RpcEndpointRef, RpcAddress}
+import org.apache.spark.rpc.{RpcAddress, RpcEndpointRef}
 
 /**
  * Grouping of data for an executor used by CoarseGrainedSchedulerBackend.
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/SimrSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/SimrSchedulerBackend.scala
index 781ecfff7e..0a6f2c01c1 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/SimrSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/SimrSchedulerBackend.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.scheduler.cluster
 
-import org.apache.hadoop.fs.{Path, FileSystem}
+import org.apache.hadoop.fs.{FileSystem, Path}
 
 import org.apache.spark.{Logging, SparkContext}
 import org.apache.spark.deploy.SparkHadoopUtil
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/SparkDeploySchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/SparkDeploySchedulerBackend.scala
index 1209cce6d1..16f3316378 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/SparkDeploySchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/SparkDeploySchedulerBackend.scala
@@ -19,11 +19,11 @@ package org.apache.spark.scheduler.cluster
 
 import java.util.concurrent.Semaphore
 
-import org.apache.spark.rpc.{RpcEndpointAddress, RpcAddress}
 import org.apache.spark.{Logging, SparkConf, SparkContext, SparkEnv}
 import org.apache.spark.deploy.{ApplicationDescription, Command}
 import org.apache.spark.deploy.client.{AppClient, AppClientListener}
 import org.apache.spark.launcher.{LauncherBackend, SparkAppHandle}
+import org.apache.spark.rpc.{RpcAddress, RpcEndpointAddress}
 import org.apache.spark.scheduler._
 import org.apache.spark.util.Utils
 
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
index a4ed85cd2a..58c30e7d97 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
@@ -18,20 +18,20 @@
 package org.apache.spark.scheduler.cluster.mesos
 
 import java.io.File
-import java.util.concurrent.locks.ReentrantLock
 import java.util.{Collections, List => JList}
+import java.util.concurrent.locks.ReentrantLock
 
 import scala.collection.JavaConverters._
 import scala.collection.mutable.{HashMap, HashSet}
 
 import com.google.common.collect.HashBiMap
-import org.apache.mesos.Protos.{TaskInfo => MesosTaskInfo, _}
 import org.apache.mesos.{Scheduler => MScheduler, SchedulerDriver}
+import org.apache.mesos.Protos.{TaskInfo => MesosTaskInfo, _}
 
 import org.apache.spark.{SecurityManager, SparkContext, SparkEnv, SparkException, TaskState}
 import org.apache.spark.network.netty.SparkTransportConf
 import org.apache.spark.network.shuffle.mesos.MesosExternalShuffleClient
-import org.apache.spark.rpc.{RpcEndpointAddress, RpcAddress}
+import org.apache.spark.rpc.{RpcAddress, RpcEndpointAddress}
 import org.apache.spark.scheduler.{SlaveLost, TaskSchedulerImpl}
 import org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend
 import org.apache.spark.util.Utils
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala
index 16815d51d4..05fda0fded 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala
@@ -24,16 +24,16 @@ import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 
+import org.apache.mesos.{Scheduler, SchedulerDriver}
+import org.apache.mesos.Protos.{TaskState => MesosTaskState, _}
 import org.apache.mesos.Protos.Environment.Variable
 import org.apache.mesos.Protos.TaskStatus.Reason
-import org.apache.mesos.Protos.{TaskState => MesosTaskState, _}
-import org.apache.mesos.{Scheduler, SchedulerDriver}
+
+import org.apache.spark.{SecurityManager, SparkConf, SparkException, TaskState}
 import org.apache.spark.deploy.mesos.MesosDriverDescription
 import org.apache.spark.deploy.rest.{CreateSubmissionResponse, KillSubmissionResponse, SubmissionStatusResponse}
 import org.apache.spark.metrics.MetricsSystem
 import org.apache.spark.util.Utils
-import org.apache.spark.{SecurityManager, SparkConf, SparkException, TaskState}
-
 
 /**
  * Tracks the current state of a Mesos Task that runs a Spark driver.
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
index 281965a598..eaf0cb06d6 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
@@ -26,6 +26,7 @@ import scala.collection.mutable.{HashMap, HashSet}
 import org.apache.mesos.{Scheduler => MScheduler, _}
 import org.apache.mesos.Protos.{ExecutorInfo => MesosExecutorInfo, TaskInfo => MesosTaskInfo, _}
 import org.apache.mesos.protobuf.ByteString
+
 import org.apache.spark.{SparkContext, SparkException, TaskState}
 import org.apache.spark.executor.MesosExecutorBackend
 import org.apache.spark.scheduler._
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
index 721861fbbc..010caff3e3 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
@@ -25,12 +25,12 @@ import scala.collection.mutable.ArrayBuffer
 import scala.util.control.NonFatal
 
 import com.google.common.base.Splitter
-import org.apache.mesos.{MesosSchedulerDriver, SchedulerDriver, Scheduler, Protos}
+import org.apache.mesos.{MesosSchedulerDriver, Protos, Scheduler, SchedulerDriver}
 import org.apache.mesos.Protos._
 import org.apache.mesos.protobuf.{ByteString, GeneratedMessage}
-import org.apache.spark.{SparkException, SparkConf, Logging, SparkContext}
-import org.apache.spark.util.Utils
 
+import org.apache.spark.{Logging, SparkConf, SparkContext, SparkException}
+import org.apache.spark.util.Utils
 
 /**
  * Shared trait for implementing a Mesos Scheduler. This holds common state and helper
diff --git a/core/src/main/scala/org/apache/spark/serializer/GenericAvroSerializer.scala b/core/src/main/scala/org/apache/spark/serializer/GenericAvroSerializer.scala
index 8d6af9cae8..3d5b7105f0 100644
--- a/core/src/main/scala/org/apache/spark/serializer/GenericAvroSerializer.scala
+++ b/core/src/main/scala/org/apache/spark/serializer/GenericAvroSerializer.scala
@@ -29,7 +29,7 @@ import org.apache.avro.generic.{GenericData, GenericRecord}
 import org.apache.avro.io._
 import org.apache.commons.io.IOUtils
 
-import org.apache.spark.{SparkException, SparkEnv}
+import org.apache.spark.{SparkEnv, SparkException}
 import org.apache.spark.io.CompressionCodec
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala b/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala
index 1b4538e6af..bc9fd50c2c 100644
--- a/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala
+++ b/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.serializer
 
-import java.io.{DataInput, DataOutput, EOFException, IOException, InputStream, OutputStream}
+import java.io.{DataInput, DataOutput, EOFException, InputStream, IOException, OutputStream}
 import java.nio.ByteBuffer
 import javax.annotation.Nullable
 
@@ -25,9 +25,9 @@ import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.reflect.ClassTag
 
+import com.esotericsoftware.kryo.{Kryo, KryoException, Serializer => KryoClassSerializer}
 import com.esotericsoftware.kryo.io.{Input => KryoInput, Output => KryoOutput}
 import com.esotericsoftware.kryo.serializers.{JavaSerializer => KryoJavaSerializer}
-import com.esotericsoftware.kryo.{Kryo, KryoException, Serializer => KryoClassSerializer}
 import com.twitter.chill.{AllScalaRegistrar, EmptyScalaKryoInstantiator}
 import org.apache.avro.generic.{GenericData, GenericRecord}
 import org.roaringbitmap.RoaringBitmap
@@ -37,8 +37,8 @@ import org.apache.spark.api.python.PythonBroadcast
 import org.apache.spark.network.util.ByteUnit
 import org.apache.spark.scheduler.{CompressedMapStatus, HighlyCompressedMapStatus}
 import org.apache.spark.storage._
-import org.apache.spark.util.collection.CompactBuffer
 import org.apache.spark.util.{BoundedPriorityQueue, SerializableConfiguration, SerializableJobConf, Utils}
+import org.apache.spark.util.collection.CompactBuffer
 
 /**
  * A Spark serializer that uses the [[https://code.google.com/p/kryo/ Kryo serialization library]].
diff --git a/core/src/main/scala/org/apache/spark/serializer/Serializer.scala b/core/src/main/scala/org/apache/spark/serializer/Serializer.scala
index bd2704dc81..90c0728557 100644
--- a/core/src/main/scala/org/apache/spark/serializer/Serializer.scala
+++ b/core/src/main/scala/org/apache/spark/serializer/Serializer.scala
@@ -25,7 +25,7 @@ import scala.reflect.ClassTag
 
 import org.apache.spark.{SparkConf, SparkEnv}
 import org.apache.spark.annotation.{DeveloperApi, Private}
-import org.apache.spark.util.{Utils, ByteBufferInputStream, NextIterator}
+import org.apache.spark.util.{ByteBufferInputStream, NextIterator, Utils}
 
 /**
  * :: DeveloperApi ::
diff --git a/core/src/main/scala/org/apache/spark/shuffle/BaseShuffleHandle.scala b/core/src/main/scala/org/apache/spark/shuffle/BaseShuffleHandle.scala
index b36c457d6d..0a65bbf8dd 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/BaseShuffleHandle.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/BaseShuffleHandle.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.shuffle
 
-import org.apache.spark.{ShuffleDependency, Aggregator, Partitioner}
+import org.apache.spark.{Aggregator, Partitioner, ShuffleDependency}
 import org.apache.spark.serializer.Serializer
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/shuffle/FetchFailedException.scala b/core/src/main/scala/org/apache/spark/shuffle/FetchFailedException.scala
index be184464e0..b2d050b218 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/FetchFailedException.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/FetchFailedException.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.shuffle
 
-import org.apache.spark.storage.BlockManagerId
 import org.apache.spark.{FetchFailed, TaskEndReason}
+import org.apache.spark.storage.BlockManagerId
 import org.apache.spark.util.Utils
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala b/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala
index cc5f933393..7abcb29672 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala
@@ -21,13 +21,13 @@ import java.util.concurrent.ConcurrentLinkedQueue
 
 import scala.collection.JavaConverters._
 
+import org.apache.spark.{Logging, SparkConf, SparkEnv}
 import org.apache.spark.executor.ShuffleWriteMetrics
 import org.apache.spark.network.buffer.{FileSegmentManagedBuffer, ManagedBuffer}
 import org.apache.spark.network.netty.SparkTransportConf
 import org.apache.spark.serializer.Serializer
 import org.apache.spark.storage._
 import org.apache.spark.util.{MetadataCleaner, MetadataCleanerType, TimeStampedHashMap, Utils}
-import org.apache.spark.{Logging, SparkConf, SparkEnv}
 
 /** A group of writers for a ShuffleMapTask, one writer per reducer. */
 private[spark] trait ShuffleWriterGroup {
diff --git a/core/src/main/scala/org/apache/spark/shuffle/IndexShuffleBlockResolver.scala b/core/src/main/scala/org/apache/spark/shuffle/IndexShuffleBlockResolver.scala
index fadb8fe7ed..68aba52fd7 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/IndexShuffleBlockResolver.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/IndexShuffleBlockResolver.scala
@@ -21,12 +21,12 @@ import java.io._
 
 import com.google.common.io.ByteStreams
 
+import org.apache.spark.{Logging, SparkConf, SparkEnv}
 import org.apache.spark.network.buffer.{FileSegmentManagedBuffer, ManagedBuffer}
 import org.apache.spark.network.netty.SparkTransportConf
 import org.apache.spark.shuffle.IndexShuffleBlockResolver.NOOP_REDUCE_ID
 import org.apache.spark.storage._
 import org.apache.spark.util.Utils
-import org.apache.spark.{SparkEnv, Logging, SparkConf}
 
 /**
  * Create and maintain the shuffle blocks' mapping between logic block and physical file location.
diff --git a/core/src/main/scala/org/apache/spark/shuffle/ShuffleBlockResolver.scala b/core/src/main/scala/org/apache/spark/shuffle/ShuffleBlockResolver.scala
index 4342b0d598..81aea33ee4 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/ShuffleBlockResolver.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/ShuffleBlockResolver.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.shuffle
 
 import java.nio.ByteBuffer
+
 import org.apache.spark.network.buffer.ManagedBuffer
 import org.apache.spark.storage.ShuffleBlockId
 
diff --git a/core/src/main/scala/org/apache/spark/shuffle/ShuffleManager.scala b/core/src/main/scala/org/apache/spark/shuffle/ShuffleManager.scala
index a3444bf4da..76fd249fbd 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/ShuffleManager.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/ShuffleManager.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.shuffle
 
-import org.apache.spark.{TaskContext, ShuffleDependency}
+import org.apache.spark.{ShuffleDependency, TaskContext}
 
 /**
  * Pluggable interface for shuffle systems. A ShuffleManager is created in SparkEnv on the driver
diff --git a/core/src/main/scala/org/apache/spark/status/api/v1/AllStagesResource.scala b/core/src/main/scala/org/apache/spark/status/api/v1/AllStagesResource.scala
index 31b4dd7c0f..341ae78236 100644
--- a/core/src/main/scala/org/apache/spark/status/api/v1/AllStagesResource.scala
+++ b/core/src/main/scala/org/apache/spark/status/api/v1/AllStagesResource.scala
@@ -17,8 +17,8 @@
 package org.apache.spark.status.api.v1
 
 import java.util.{Arrays, Date, List => JList}
-import javax.ws.rs.core.MediaType
 import javax.ws.rs.{GET, Produces, QueryParam}
+import javax.ws.rs.core.MediaType
 
 import org.apache.spark.executor.{InputMetrics => InternalInputMetrics, OutputMetrics => InternalOutputMetrics, ShuffleReadMetrics => InternalShuffleReadMetrics, ShuffleWriteMetrics => InternalShuffleWriteMetrics, TaskMetrics => InternalTaskMetrics}
 import org.apache.spark.scheduler.{AccumulableInfo => InternalAccumulableInfo, StageInfo}
diff --git a/core/src/main/scala/org/apache/spark/status/api/v1/OneApplicationResource.scala b/core/src/main/scala/org/apache/spark/status/api/v1/OneApplicationResource.scala
index b5ef72649e..d7e6a8b589 100644
--- a/core/src/main/scala/org/apache/spark/status/api/v1/OneApplicationResource.scala
+++ b/core/src/main/scala/org/apache/spark/status/api/v1/OneApplicationResource.scala
@@ -16,8 +16,8 @@
  */
 package org.apache.spark.status.api.v1
 
+import javax.ws.rs.{GET, PathParam, Produces}
 import javax.ws.rs.core.MediaType
-import javax.ws.rs.{Produces, PathParam, GET}
 
 @Produces(Array(MediaType.APPLICATION_JSON))
 private[v1] class OneApplicationResource(uiRoot: UIRoot) {
diff --git a/core/src/main/scala/org/apache/spark/status/api/v1/OneJobResource.scala b/core/src/main/scala/org/apache/spark/status/api/v1/OneJobResource.scala
index 6d8a60d480..a0f6360bc5 100644
--- a/core/src/main/scala/org/apache/spark/status/api/v1/OneJobResource.scala
+++ b/core/src/main/scala/org/apache/spark/status/api/v1/OneJobResource.scala
@@ -16,7 +16,7 @@
  */
 package org.apache.spark.status.api.v1
 
-import javax.ws.rs.{PathParam, GET, Produces}
+import javax.ws.rs.{GET, PathParam, Produces}
 import javax.ws.rs.core.MediaType
 
 import org.apache.spark.JobExecutionStatus
diff --git a/core/src/main/scala/org/apache/spark/status/api/v1/OneRDDResource.scala b/core/src/main/scala/org/apache/spark/status/api/v1/OneRDDResource.scala
index dfdc09c6ca..237aeac185 100644
--- a/core/src/main/scala/org/apache/spark/status/api/v1/OneRDDResource.scala
+++ b/core/src/main/scala/org/apache/spark/status/api/v1/OneRDDResource.scala
@@ -16,7 +16,7 @@
  */
 package org.apache.spark.status.api.v1
 
-import javax.ws.rs.{PathParam, GET, Produces}
+import javax.ws.rs.{GET, PathParam, Produces}
 import javax.ws.rs.core.MediaType
 
 import org.apache.spark.ui.SparkUI
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 b5b7804d54..8caf9e5535 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManager.scala
@@ -21,8 +21,8 @@ import java.io._
 import java.nio.{ByteBuffer, MappedByteBuffer}
 
 import scala.collection.mutable.{ArrayBuffer, HashMap}
-import scala.concurrent.duration._
 import scala.concurrent.{Await, ExecutionContext, Future}
+import scala.concurrent.duration._
 import scala.util.Random
 import scala.util.control.NonFatal
 
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 440c4c18aa..da1de11d60 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMaster.scala
@@ -21,10 +21,10 @@ import scala.collection.Iterable
 import scala.collection.generic.CanBuildFrom
 import scala.concurrent.{Await, Future}
 
-import org.apache.spark.rpc.RpcEndpointRef
 import org.apache.spark.{Logging, SparkConf, SparkException}
+import org.apache.spark.rpc.RpcEndpointRef
 import org.apache.spark.storage.BlockManagerMessages._
-import org.apache.spark.util.{ThreadUtils, RpcUtils}
+import org.apache.spark.util.{RpcUtils, ThreadUtils}
 
 private[spark]
 class BlockManagerMaster(
diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala b/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
index 41892b4ffc..4db400a344 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
@@ -23,9 +23,9 @@ import scala.collection.mutable
 import scala.collection.JavaConverters._
 import scala.concurrent.{ExecutionContext, Future}
 
-import org.apache.spark.rpc.{RpcEndpointRef, RpcEnv, RpcCallContext, ThreadSafeRpcEndpoint}
 import org.apache.spark.{Logging, SparkConf}
 import org.apache.spark.annotation.DeveloperApi
+import org.apache.spark.rpc.{RpcCallContext, RpcEndpointRef, RpcEnv, ThreadSafeRpcEndpoint}
 import org.apache.spark.scheduler._
 import org.apache.spark.storage.BlockManagerMessages._
 import org.apache.spark.util.{ThreadUtils, Utils}
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 f7e84a2c2e..4daf22f714 100644
--- a/core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/DiskBlockManager.scala
@@ -17,10 +17,10 @@
 
 package org.apache.spark.storage
 
+import java.io.{File, IOException}
 import java.util.UUID
-import java.io.{IOException, File}
 
-import org.apache.spark.{SparkConf, Logging}
+import org.apache.spark.{Logging, SparkConf}
 import org.apache.spark.executor.ExecutorExitCode
 import org.apache.spark.util.{ShutdownHookManager, Utils}
 
diff --git a/core/src/main/scala/org/apache/spark/storage/DiskBlockObjectWriter.scala b/core/src/main/scala/org/apache/spark/storage/DiskBlockObjectWriter.scala
index e2dd80f243..e36a367323 100644
--- a/core/src/main/scala/org/apache/spark/storage/DiskBlockObjectWriter.scala
+++ b/core/src/main/scala/org/apache/spark/storage/DiskBlockObjectWriter.scala
@@ -17,12 +17,12 @@
 
 package org.apache.spark.storage
 
-import java.io.{BufferedOutputStream, FileOutputStream, File, OutputStream}
+import java.io.{BufferedOutputStream, File, FileOutputStream, OutputStream}
 import java.nio.channels.FileChannel
 
 import org.apache.spark.Logging
-import org.apache.spark.serializer.{SerializerInstance, SerializationStream}
 import org.apache.spark.executor.ShuffleWriteMetrics
+import org.apache.spark.serializer.{SerializationStream, SerializerInstance}
 import org.apache.spark.util.Utils
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/storage/DiskStore.scala b/core/src/main/scala/org/apache/spark/storage/DiskStore.scala
index 6c4477184d..1f3f193f2f 100644
--- a/core/src/main/scala/org/apache/spark/storage/DiskStore.scala
+++ b/core/src/main/scala/org/apache/spark/storage/DiskStore.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.storage
 
-import java.io.{IOException, File, FileOutputStream, RandomAccessFile}
+import java.io.{File, FileOutputStream, IOException, RandomAccessFile}
 import java.nio.ByteBuffer
 import java.nio.channels.FileChannel.MapMode
 
diff --git a/core/src/main/scala/org/apache/spark/storage/RDDInfo.scala b/core/src/main/scala/org/apache/spark/storage/RDDInfo.scala
index 94e8559bd2..673f7ad79d 100644
--- a/core/src/main/scala/org/apache/spark/storage/RDDInfo.scala
+++ b/core/src/main/scala/org/apache/spark/storage/RDDInfo.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.storage
 
 import org.apache.spark.annotation.DeveloperApi
-import org.apache.spark.rdd.{RDDOperationScope, RDD}
+import org.apache.spark.rdd.{RDD, RDDOperationScope}
 import org.apache.spark.util.{CallSite, Utils}
 
 @DeveloperApi
diff --git a/core/src/main/scala/org/apache/spark/storage/TachyonBlockManager.scala b/core/src/main/scala/org/apache/spark/storage/TachyonBlockManager.scala
index 7f88f2fe6d..6aa7e13901 100644
--- a/core/src/main/scala/org/apache/spark/storage/TachyonBlockManager.scala
+++ b/core/src/main/scala/org/apache/spark/storage/TachyonBlockManager.scala
@@ -25,7 +25,6 @@ import java.util.{Date, Random}
 import scala.util.control.NonFatal
 
 import com.google.common.io.ByteStreams
-
 import tachyon.{Constants, TachyonURI}
 import tachyon.client.ClientContext
 import tachyon.client.file.{TachyonFile, TachyonFileSystem}
@@ -38,7 +37,6 @@ import org.apache.spark.Logging
 import org.apache.spark.executor.ExecutorExitCode
 import org.apache.spark.util.Utils
 
-
 /**
  * Creates and maintains the logical mapping between logical blocks and tachyon fs locations. By
  * default, one block is mapped to one file with a name given by its BlockId.
diff --git a/core/src/main/scala/org/apache/spark/ui/SparkUI.scala b/core/src/main/scala/org/apache/spark/ui/SparkUI.scala
index 8da6884a38..e319937702 100644
--- a/core/src/main/scala/org/apache/spark/ui/SparkUI.scala
+++ b/core/src/main/scala/org/apache/spark/ui/SparkUI.scala
@@ -21,18 +21,18 @@ import java.util.{Date, ServiceLoader}
 
 import scala.collection.JavaConverters._
 
-import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationAttemptInfo, ApplicationInfo,
-  UIRoot}
-import org.apache.spark.util.Utils
 import org.apache.spark.{Logging, SecurityManager, SparkConf, SparkContext}
 import org.apache.spark.scheduler._
+import org.apache.spark.status.api.v1.{ApiRootResource, ApplicationAttemptInfo, ApplicationInfo,
+  UIRoot}
 import org.apache.spark.storage.StorageStatusListener
 import org.apache.spark.ui.JettyUtils._
 import org.apache.spark.ui.env.{EnvironmentListener, EnvironmentTab}
 import org.apache.spark.ui.exec.{ExecutorsListener, ExecutorsTab}
-import org.apache.spark.ui.jobs.{JobsTab, JobProgressListener, StagesTab}
-import org.apache.spark.ui.storage.{StorageListener, StorageTab}
+import org.apache.spark.ui.jobs.{JobProgressListener, JobsTab, StagesTab}
 import org.apache.spark.ui.scope.RDDOperationGraphListener
+import org.apache.spark.ui.storage.{StorageListener, StorageTab}
+import org.apache.spark.util.Utils
 
 /**
  * Top level user interface for a Spark application.
diff --git a/core/src/main/scala/org/apache/spark/ui/WebUI.scala b/core/src/main/scala/org/apache/spark/ui/WebUI.scala
index 81a121fd44..3925235984 100644
--- a/core/src/main/scala/org/apache/spark/ui/WebUI.scala
+++ b/core/src/main/scala/org/apache/spark/ui/WebUI.scala
@@ -26,9 +26,9 @@ import scala.xml.Node
 import org.eclipse.jetty.servlet.ServletContextHandler
 import org.json4s.JsonAST.{JNothing, JValue}
 
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.ui.JettyUtils._
 import org.apache.spark.util.Utils
-import org.apache.spark.{Logging, SecurityManager, SparkConf}
 
 /**
  * The top level component of the UI hierarchy that contains the server.
diff --git a/core/src/main/scala/org/apache/spark/ui/exec/ExecutorThreadDumpPage.scala b/core/src/main/scala/org/apache/spark/ui/exec/ExecutorThreadDumpPage.scala
index 58575d154c..1a6f0fdd50 100644
--- a/core/src/main/scala/org/apache/spark/ui/exec/ExecutorThreadDumpPage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/exec/ExecutorThreadDumpPage.scala
@@ -21,7 +21,7 @@ import java.net.URLDecoder
 import javax.servlet.http.HttpServletRequest
 
 import scala.util.Try
-import scala.xml.{Text, Node}
+import scala.xml.{Node, Text}
 
 import org.apache.spark.ui.{UIUtils, WebUIPage}
 
diff --git a/core/src/main/scala/org/apache/spark/ui/exec/ExecutorsTab.scala b/core/src/main/scala/org/apache/spark/ui/exec/ExecutorsTab.scala
index a88fc4c37d..2d955a6660 100644
--- a/core/src/main/scala/org/apache/spark/ui/exec/ExecutorsTab.scala
+++ b/core/src/main/scala/org/apache/spark/ui/exec/ExecutorsTab.scala
@@ -19,7 +19,7 @@ package org.apache.spark.ui.exec
 
 import scala.collection.mutable.HashMap
 
-import org.apache.spark.{Resubmitted, ExceptionFailure, SparkContext}
+import org.apache.spark.{ExceptionFailure, Resubmitted, SparkContext}
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.scheduler._
 import org.apache.spark.storage.{StorageStatus, StorageStatusListener}
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala
index d467dd9e1f..db9912bc81 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala
@@ -24,8 +24,8 @@ import scala.collection.mutable.{HashMap, ListBuffer}
 import scala.xml._
 
 import org.apache.spark.JobExecutionStatus
-import org.apache.spark.ui.jobs.UIData.{ExecutorUIData, JobUIData}
 import org.apache.spark.ui.{ToolTips, UIUtils, WebUIPage}
+import org.apache.spark.ui.jobs.UIData.{ExecutorUIData, JobUIData}
 
 /** Page showing list of all ongoing and recently finished jobs */
 private[ui] class AllJobsPage(parent: JobsTab) extends WebUIPage("") {
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/AllStagesPage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/AllStagesPage.scala
index 5e52942b64..e75f1c57a6 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/AllStagesPage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/AllStagesPage.scala
@@ -22,7 +22,7 @@ import javax.servlet.http.HttpServletRequest
 import scala.xml.{Node, NodeSeq}
 
 import org.apache.spark.scheduler.Schedulable
-import org.apache.spark.ui.{WebUIPage, UIUtils}
+import org.apache.spark.ui.{UIUtils, WebUIPage}
 
 /** Page showing list of all ongoing and recently finished stages and pools */
 private[ui] class AllStagesPage(parent: StagesTab) extends WebUIPage("") {
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala b/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala
index 1268f44596..1304efd8f2 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.ui.jobs
 
 import scala.collection.mutable
-import scala.xml.{Unparsed, Node}
+import scala.xml.{Node, Unparsed}
 
 import org.apache.spark.ui.{ToolTips, UIUtils}
 import org.apache.spark.ui.jobs.UIData.StageUIData
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/JobPage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/JobPage.scala
index 2cad0a7969..654d988807 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/JobPage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/JobPage.scala
@@ -18,11 +18,10 @@
 package org.apache.spark.ui.jobs
 
 import java.util.Date
+import javax.servlet.http.HttpServletRequest
 
 import scala.collection.mutable.{Buffer, HashMap, ListBuffer}
-import scala.xml.{NodeSeq, Node, Unparsed, Utility}
-
-import javax.servlet.http.HttpServletRequest
+import scala.xml.{Node, NodeSeq, Unparsed, Utility}
 
 import org.apache.spark.JobExecutionStatus
 import org.apache.spark.scheduler.StageInfo
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/PoolPage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/PoolPage.scala
index f3e0b38523..fa30f2bda4 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/PoolPage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/PoolPage.scala
@@ -22,7 +22,7 @@ import javax.servlet.http.HttpServletRequest
 import scala.xml.Node
 
 import org.apache.spark.scheduler.StageInfo
-import org.apache.spark.ui.{WebUIPage, UIUtils}
+import org.apache.spark.ui.{UIUtils, WebUIPage}
 
 /** Page showing specific pool details */
 private[ui] class PoolPage(parent: StagesTab) extends WebUIPage("pool") {
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala b/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
index 08e7576b0c..2cc6c75a9a 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala
@@ -31,7 +31,7 @@ import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.scheduler.{AccumulableInfo, TaskInfo, TaskLocality}
 import org.apache.spark.ui._
 import org.apache.spark.ui.jobs.UIData._
-import org.apache.spark.util.{Utils, Distribution}
+import org.apache.spark.util.{Distribution, Utils}
 
 /** Page showing statistics and task list for a given stage */
 private[ui] class StagePage(parent: StagesTab) extends WebUIPage("stage") {
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 f008d40180..78165d7b74 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
@@ -17,14 +17,14 @@
 
 package org.apache.spark.ui.jobs
 
+import scala.collection.mutable
+import scala.collection.mutable.HashMap
+
 import org.apache.spark.JobExecutionStatus
 import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.scheduler.{AccumulableInfo, TaskInfo}
 import org.apache.spark.util.collection.OpenHashSet
 
-import scala.collection.mutable
-import scala.collection.mutable.HashMap
-
 private[spark] object UIData {
 
   class ExecutorSummary {
diff --git a/core/src/main/scala/org/apache/spark/ui/scope/RDDOperationGraph.scala b/core/src/main/scala/org/apache/spark/ui/scope/RDDOperationGraph.scala
index e9c8a8e299..06da74f1b6 100644
--- a/core/src/main/scala/org/apache/spark/ui/scope/RDDOperationGraph.scala
+++ b/core/src/main/scala/org/apache/spark/ui/scope/RDDOperationGraph.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.ui.scope
 
 import scala.collection.mutable
-import scala.collection.mutable.{StringBuilder, ListBuffer}
+import scala.collection.mutable.{ListBuffer, StringBuilder}
 
 import org.apache.spark.Logging
 import org.apache.spark.scheduler.StageInfo
diff --git a/core/src/main/scala/org/apache/spark/ui/storage/StorageTab.scala b/core/src/main/scala/org/apache/spark/ui/storage/StorageTab.scala
index 22e2993b3b..2d9b885c68 100644
--- a/core/src/main/scala/org/apache/spark/ui/storage/StorageTab.scala
+++ b/core/src/main/scala/org/apache/spark/ui/storage/StorageTab.scala
@@ -20,9 +20,9 @@ package org.apache.spark.ui.storage
 import scala.collection.mutable
 
 import org.apache.spark.annotation.DeveloperApi
-import org.apache.spark.ui._
 import org.apache.spark.scheduler._
 import org.apache.spark.storage._
+import org.apache.spark.ui._
 
 /** Web UI showing storage status of all RDD's in the given SparkContext. */
 private[ui] class StorageTab(parent: SparkUI) extends SparkUITab(parent, "storage") {
diff --git a/core/src/main/scala/org/apache/spark/util/AsynchronousListenerBus.scala b/core/src/main/scala/org/apache/spark/util/AsynchronousListenerBus.scala
index 6c1fca71f2..f6b7ea2f37 100644
--- a/core/src/main/scala/org/apache/spark/util/AsynchronousListenerBus.scala
+++ b/core/src/main/scala/org/apache/spark/util/AsynchronousListenerBus.scala
@@ -19,6 +19,7 @@ package org.apache.spark.util
 
 import java.util.concurrent._
 import java.util.concurrent.atomic.AtomicBoolean
+
 import scala.util.DynamicVariable
 
 import org.apache.spark.SparkContext
diff --git a/core/src/main/scala/org/apache/spark/util/EventLoop.scala b/core/src/main/scala/org/apache/spark/util/EventLoop.scala
index e9b2b8d24b..542c5fccf4 100644
--- a/core/src/main/scala/org/apache/spark/util/EventLoop.scala
+++ b/core/src/main/scala/org/apache/spark/util/EventLoop.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.util
 
-import java.util.concurrent.atomic.AtomicBoolean
 import java.util.concurrent.{BlockingQueue, LinkedBlockingDeque}
+import java.util.concurrent.atomic.AtomicBoolean
 
 import scala.util.control.NonFatal
 
diff --git a/core/src/main/scala/org/apache/spark/util/JsonProtocol.scala b/core/src/main/scala/org/apache/spark/util/JsonProtocol.scala
index cb0f1bf79f..a62fd2f339 100644
--- a/core/src/main/scala/org/apache/spark/util/JsonProtocol.scala
+++ b/core/src/main/scala/org/apache/spark/util/JsonProtocol.scala
@@ -25,8 +25,8 @@ import scala.collection.Map
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.module.scala.DefaultScalaModule
 import org.json4s.DefaultFormats
-import org.json4s.JsonDSL._
 import org.json4s.JsonAST._
+import org.json4s.JsonDSL._
 import org.json4s.jackson.JsonMethods._
 
 import org.apache.spark._
diff --git a/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala b/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala
index 945217203b..0a3180da87 100644
--- a/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala
+++ b/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.util
 
-import java.net.{URLClassLoader, URL}
+import java.net.{URL, URLClassLoader}
 import java.util.Enumeration
 import java.util.concurrent.ConcurrentHashMap
 
diff --git a/core/src/main/scala/org/apache/spark/util/ShutdownHookManager.scala b/core/src/main/scala/org/apache/spark/util/ShutdownHookManager.scala
index acc24ca0fb..38523be791 100644
--- a/core/src/main/scala/org/apache/spark/util/ShutdownHookManager.scala
+++ b/core/src/main/scala/org/apache/spark/util/ShutdownHookManager.scala
@@ -23,6 +23,7 @@ import java.util.PriorityQueue
 import scala.util.Try
 
 import org.apache.hadoop.fs.FileSystem
+
 import org.apache.spark.Logging
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala b/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala
index 09864e3f83..52587d2188 100644
--- a/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala
+++ b/core/src/main/scala/org/apache/spark/util/SizeEstimator.scala
@@ -17,8 +17,6 @@
 
 package org.apache.spark.util
 
-import com.google.common.collect.MapMaker
-
 import java.lang.management.ManagementFactory
 import java.lang.reflect.{Field, Modifier}
 import java.util.{IdentityHashMap, Random}
@@ -27,6 +25,8 @@ import java.util.concurrent.ConcurrentHashMap
 import scala.collection.mutable.ArrayBuffer
 import scala.runtime.ScalaRunTime
 
+import com.google.common.collect.MapMaker
+
 import org.apache.spark.Logging
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.util.collection.OpenHashSet
diff --git a/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala b/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala
index d7e5143c30..1733025041 100644
--- a/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala
+++ b/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.util
 
-import java.util.Set
 import java.util.Map.Entry
+import java.util.Set
 import java.util.concurrent.ConcurrentHashMap
 
 import scala.collection.JavaConverters._
diff --git a/core/src/main/scala/org/apache/spark/util/Utils.scala b/core/src/main/scala/org/apache/spark/util/Utils.scala
index 9bdcc4d817..9ecbffbf71 100644
--- a/core/src/main/scala/org/apache/spark/util/Utils.scala
+++ b/core/src/main/scala/org/apache/spark/util/Utils.scala
@@ -22,8 +22,8 @@ import java.lang.management.ManagementFactory
 import java.net._
 import java.nio.ByteBuffer
 import java.nio.channels.Channels
-import java.util.concurrent._
 import java.util.{Locale, Properties, Random, UUID}
+import java.util.concurrent._
 import javax.net.ssl.HttpsURLConnection
 
 import scala.collection.JavaConverters._
diff --git a/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala b/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
index f6d81ee5bf..4a44481cf4 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
@@ -28,12 +28,12 @@ import com.google.common.io.ByteStreams
 
 import org.apache.spark.{Logging, SparkEnv, TaskContext}
 import org.apache.spark.annotation.DeveloperApi
+import org.apache.spark.executor.ShuffleWriteMetrics
 import org.apache.spark.memory.TaskMemoryManager
 import org.apache.spark.serializer.{DeserializationStream, Serializer}
 import org.apache.spark.storage.{BlockId, BlockManager}
 import org.apache.spark.util.CompletionIterator
 import org.apache.spark.util.collection.ExternalAppendOnlyMap.HashComparator
-import org.apache.spark.executor.ShuffleWriteMetrics
 
 /**
  * :: DeveloperApi ::
diff --git a/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala b/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala
index 44b1d90667..63ba954a7f 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala
@@ -20,15 +20,15 @@ package org.apache.spark.util.collection
 import java.io._
 import java.util.Comparator
 
-import scala.collection.mutable.ArrayBuffer
 import scala.collection.mutable
+import scala.collection.mutable.ArrayBuffer
 
 import com.google.common.io.ByteStreams
 
 import org.apache.spark._
+import org.apache.spark.executor.ShuffleWriteMetrics
 import org.apache.spark.memory.TaskMemoryManager
 import org.apache.spark.serializer._
-import org.apache.spark.executor.ShuffleWriteMetrics
 import org.apache.spark.storage.{BlockId, DiskBlockObjectWriter}
 
 /**
diff --git a/core/src/main/scala/org/apache/spark/util/collection/OpenHashSet.scala b/core/src/main/scala/org/apache/spark/util/collection/OpenHashSet.scala
index 60bf4dd746..0f6a425e3d 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/OpenHashSet.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/OpenHashSet.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.util.collection
 
 import scala.reflect._
+
 import com.google.common.hash.Hashing
 
 import org.apache.spark.annotation.Private
diff --git a/core/src/main/scala/org/apache/spark/util/collection/Spillable.scala b/core/src/main/scala/org/apache/spark/util/collection/Spillable.scala
index 3a48af82b1..e1592184ca 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/Spillable.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/Spillable.scala
@@ -17,8 +17,8 @@
 
 package org.apache.spark.util.collection
 
-import org.apache.spark.memory.{MemoryMode, TaskMemoryManager}
 import org.apache.spark.{Logging, SparkEnv}
+import org.apache.spark.memory.{MemoryMode, TaskMemoryManager}
 
 /**
  * Spills contents of an in-memory collection to disk when the memory threshold
diff --git a/core/src/main/scala/org/apache/spark/util/logging/RollingFileAppender.scala b/core/src/main/scala/org/apache/spark/util/logging/RollingFileAppender.scala
index 1e8476c4a0..050ece12f1 100644
--- a/core/src/main/scala/org/apache/spark/util/logging/RollingFileAppender.scala
+++ b/core/src/main/scala/org/apache/spark/util/logging/RollingFileAppender.scala
@@ -20,8 +20,8 @@ package org.apache.spark.util.logging
 import java.io.{File, FileFilter, InputStream}
 
 import com.google.common.io.Files
+
 import org.apache.spark.SparkConf
-import RollingFileAppender._
 
 /**
  * Continuously appends data from input stream into the given file, and rolls
@@ -39,9 +39,11 @@ private[spark] class RollingFileAppender(
     activeFile: File,
     val rollingPolicy: RollingPolicy,
     conf: SparkConf,
-    bufferSize: Int = DEFAULT_BUFFER_SIZE
+    bufferSize: Int = RollingFileAppender.DEFAULT_BUFFER_SIZE
   ) extends FileAppender(inputStream, activeFile, bufferSize) {
 
+  import RollingFileAppender._
+
   private val maxRetainedFiles = conf.getInt(RETAINED_FILES_PROPERTY, -1)
 
   /** Stop the appender */
diff --git a/core/src/main/scala/org/apache/spark/util/random/RandomSampler.scala b/core/src/main/scala/org/apache/spark/util/random/RandomSampler.scala
index c156b03cdb..1314217023 100644
--- a/core/src/main/scala/org/apache/spark/util/random/RandomSampler.scala
+++ b/core/src/main/scala/org/apache/spark/util/random/RandomSampler.scala
@@ -19,8 +19,8 @@ package org.apache.spark.util.random
 
 import java.util.Random
 
-import scala.reflect.ClassTag
 import scala.collection.mutable.ArrayBuffer
+import scala.reflect.ClassTag
 
 import org.apache.commons.math3.distribution.PoissonDistribution