[GitHub] [spark] attilapiros commented on a change in pull request #23986: [SPARK-27070] Fix performance bug in DefaultPartitionCoalescer

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attilapiros commented on a change in pull request #23986: [SPARK-27070] Fix performance bug in DefaultPartitionCoalescer
URL: https://github.com/apache/spark/pull/23986#discussion_r263460077
 
 

 ##########
 File path: core/src/main/scala/org/apache/spark/rdd/CoalescedRDD.scala
 ##########
 @@ -213,15 +210,16 @@ private class DefaultPartitionCoalescer(val balanceSlack: Double = 0.10)
   }
 
   /**
-   * Sorts and gets the least element of the list associated with key in groupHash
+   * Gets the least element of the list associated with key in groupHash
    * The returned PartitionGroup is the least loaded of all groups that represent the machine "key"
    *
    * @param key string representing a partitioned group on preferred machine key
    * @return Option of [[PartitionGroup]] that has least elements for key
    */
-  def getLeastGroupHash(key: String): Option[PartitionGroup] = {
-    groupHash.get(key).map(_.sortWith(compare).head)
-  }
+  def getLeastGroupHash(key: String): Option[PartitionGroup] =
+    groupHash
 
 Review comment:
   What about avoiding `if` and `flatmap` and `Some()` , like:
   ```
       groupHash.get(key).filter(_.nonEmpty).map(_.minBy(_.numPartitions))
   ```

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