[Spark][Scala] repartition issue reproduce

repartition-reproduce.scala

import org.apache.spark.SparkContext
import org.apache.spark.SparkConf

case class Custom(a: Int, b: String)

// Set parallelism level as 2
val conf = new SparkConf().setAppName("RepartitionIssue").setMaster("local[2]")
val sc = new SparkContext(conf)

val data = Seq(Custom(1, "a"), Custom(2, "b"))
val rdd = sc.parallelize(data)
// Try to repartition data 
val mappedRDD = rdd.repartition(2)
  .mapPartitions { iter =>
    // Print out at executor-side
    iter.foreach(println)
    iter
  }
mappedRDD.collect