By default, Spark uses Java Serialization which is recognized as bad solution for the processor and memory usage on Serialization and Deserialization besides the low compression on generate bytes.
So I’m using Kryo instead of Java’s default Serializer. To be able to test your code on
spark-shell you just need to set the parameter to
$ export SPARK_JAVA_OPTS="-Dspark.serializer=org.apache.spark.serializer.KryoSerializer"
You can check if configuration was correctly applied browsing Spark’s Environment Web UI: