[GitHub] [spark] LuciferYang commented on a diff in pull request #37728: [SPARK-40276][CORE] Reduce the result size of RDD.takeOrdered

[GitBox <gi...@apache.org>]

LuciferYang commented on code in PR #37728:
URL: https://github.com/apache/spark/pull/37728#discussion_r959170859


##########
core/src/main/scala/org/apache/spark/rdd/RDD.scala:
##########
@@ -1523,22 +1523,28 @@ abstract class RDD[T: ClassTag](
    * @return an array of top elements
    */
   def takeOrdered(num: Int)(implicit ord: Ordering[T]): Array[T] = withScope {
-    if (num == 0) {
+    if (num == 0 || this.getNumPartitions == 0) {
       Array.empty
     } else {
-      val mapRDDs = mapPartitions { items =>
-        // Priority keeps the largest elements, so let's reverse the ordering.
-        val queue = new BoundedPriorityQueue[T](num)(ord.reverse)
-        queue ++= collectionUtils.takeOrdered(items, num)(ord)
-        Iterator.single(queue)
-      }
-      if (mapRDDs.partitions.length == 0) {
-        Array.empty
-      } else {
-        mapRDDs.reduce { (queue1, queue2) =>
-          queue1 ++= queue2
-          queue1
-        }.toArray.sorted(ord)
+      this.mapPartitionsWithIndex { case (pid, iter) =>
+        if (iter.nonEmpty) {
+          // Priority keeps the largest elements, so let's reverse the ordering.
+          Iterator.single(collectionUtils.takeOrdered(iter, num)(ord).toArray)

Review Comment:
   Will the same benefits when using Scala 2.13?
   
   



-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org


---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org