Initializing Spark
The first thing a Spark program must do is to create a SparkContext object, which tells Spark how to access a cluster. To create a SparkContext you first need to build a SparkConf object that contains information about your application.
Only one SparkContext may be active per JVM. You must stop() the active SparkContext before creating a new one.
val conf = new SparkConf().setAppName(appName).setMaster(master)
new SparkContext(conf)