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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