public static SparkContext getContext() {
        if (null != CONTEXT && CONTEXT.isStopped())
            recreateStopped();
        return CONTEXT;
    }
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