fix style

core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala

@@ -234,7 +234,7 @@ class ExternalAppendOnlyMap[K, V, C](
   /**
    * spill contents of memory map to disk and release its memory
    */
-  override def forceSpill(): Long  = {
+  override def forceSpill(): Long = {
     var freeMemory = 0L
     if (memoryOrDiskIter.isDefined) {
       _spillCount += 1
@@ -255,20 +255,20 @@ class ExternalAppendOnlyMap[K, V, C](
    * An iterator that read elements from in-memory iterator or disk iterator when in-memory
    * iterator have spilled to disk.
    */
-  case class MemoryOrDiskIterator(memIter: Iterator[(K,C)]) extends Iterator[(K,C)] {
+  case class MemoryOrDiskIterator(memIter: Iterator[(K, C)]) extends Iterator[(K, C)] {
 
     var currentIter = memIter
 
     override def hasNext: Boolean = currentIter.hasNext
 
     override def next(): (K, C) = currentIter.next()
 
-    def spill() = {
+    private[spark] def spill() = {
       if (hasNext) {
         currentIter = spillMemoryToDisk(currentIter)
       } else {
-        //in-memory iterator is already drained, release it by giving an empty iterator
-        currentIter = new Iterator[(K,C)]{
+        // in-memory iterator is already drained, release it by giving an empty iterator
+        currentIter = new Iterator[(K, C)]{
           override def hasNext: Boolean = false
           override def next(): (K, C) = null
         }

core/src/main/scala/org/apache/spark/util/collection/ExternalSorter.scala

@@ -651,11 +651,11 @@ private[spark] class ExternalSorter[K, V, C](
 
     override def next(): ((Int, K), C) = currentIter.next()
 
-    def spill() = {
+    private[spark] def spill() = {
       if (hasNext) {
         currentIter = spillMemoryToDisk(currentIter)
       } else {
-        //in-memory iterator is already drained, release it by giving an empty iterator
+        // in-memory iterator is already drained, release it by giving an empty iterator
         currentIter = new Iterator[((Int, K), C)]{
           override def hasNext: Boolean = false
           override def next(): ((Int, K), C) = null
@@ -671,7 +671,7 @@ private[spark] class ExternalSorter[K, V, C](
   override def forceSpill(): Long = {
     var freeMemory = 0L
     if (memoryOrDiskIter.isDefined) {
-      //has memory buffer that can be spilled
+      // has memory buffer that can be spilled
       _spillCount += 1
 
       val shouldCombine = aggregator.isDefined

core/src/test/scala/org/apache/spark/shuffle/ShuffleMemoryManagerSuite.scala

@@ -326,7 +326,6 @@ class ShuffleMemoryManagerSuite extends SparkFunSuite with Timeouts {
     val manager = new ShuffleMemoryManager(1000L)
 
     val spill1 = new FakeSpillable()
-    val spill2 = new FakeSpillable()
 
     spill1.addMemory(manager.tryToAcquire(700L))
     spill1.addMemory(manager.tryToAcquire(300L))