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diff --git a/core/src/main/scala/org/apache/spark/util/BoundedPriorityQueue.scala b/core/src/main/scala/org/apache/spark/util/BoundedPriorityQueue.scala
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+++ b/core/src/main/scala/org/apache/spark/util/BoundedPriorityQueue.scala
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.util
+
+import java.io.Serializable
+import java.util.{PriorityQueue => JPriorityQueue}
+import scala.collection.generic.Growable
+import scala.collection.JavaConverters._
+
+/**
+ * Bounded priority queue. This class wraps the original PriorityQueue
+ * class and modifies it such that only the top K elements are retained.
+ * The top K elements are defined by an implicit Ordering[A].
+ */
+class BoundedPriorityQueue[A](maxSize: Int)(implicit ord: Ordering[A])
+  extends Iterable[A] with Growable[A] with Serializable {
+
+  private val underlying = new JPriorityQueue[A](maxSize, ord)
+
+  override def iterator: Iterator[A] = underlying.iterator.asScala
+
+  override def ++=(xs: TraversableOnce[A]): this.type = {
+    xs.foreach { this += _ }
+    this
+  }
+
+  override def +=(elem: A): this.type = {
+    if (size < maxSize) underlying.offer(elem)
+    else maybeReplaceLowest(elem)
+    this
+  }
+
+  override def +=(elem1: A, elem2: A, elems: A*): this.type = {
+    this += elem1 += elem2 ++= elems
+  }
+
+  override def clear() { underlying.clear() }
+
+  private def maybeReplaceLowest(a: A): Boolean = {
+    val head = underlying.peek()
+    if (head != null && ord.gt(a, head)) {
+      underlying.poll()
+      underlying.offer(a)
+    } else false
+  }
+}
+