public static SparkContext create(final String master) {
        final SparkConf sparkConf = new SparkConf();
        sparkConf.setMaster(master);
        return Spark.create(sparkConf);
    }
This is a static cache the prevents Spark from garbage collecting unreferenced RDDs.

@author Marko A. Rodriguez (http://markorodriguez.com)
spark-gremlin/src/main/java/org/apache/tinkerpop/gremlin/spark/structure/Spark.java