Major Description
Otherwise it is pretty annoying to do a sort on types that are not java serializable.
To reproduce, just set the serializer to Kryo, and run the following job:
class JavaNonSerializableClass extends Comparable { override def compareTo(o: JavaNonSerializableClass) = 0 } sc.parallelize(Seq(new JavaNonSerializableClass, new JavaNonSerializableClass), 2).map(x => (x,x)).sortByKey()
Basically the partitioner will always be serialized using Java (by the task closure serializer). However, the rangeBounds variable in RangePartitioner should be serialized with the user specified serializer.