title: Spark job is failed due to java.io.NotSerializableException: org.apache.spark.SparkContext
body: <p>I am facing above exception when I am trying to apply a method(ComputeDwt) on <code>RDD[(Int,ArrayBuffer[(Int,Double)])]</code> input.
  I am even using <code>extends Serialization</code> option to serialize objects in spark.Here is the code snippet.</p>
  
  <pre><code>input:series:RDD[(Int,ArrayBuffer[(Int,Double)])] 
  DWTsample extends Serialization is a class having computeDwt function.
  sc: sparkContext
  
  val  kk:RDD[(Int,List[Double])]=series.map(t=&gt;(t._1,new DWTsample().computeDwt(sc,t._2)))
  
  Error:
  org.apache.spark.SparkException: Job failed: java.io.NotSerializableException: org.apache.spark.SparkContext
  org.apache.spark.SparkException: Job failed: java.io.NotSerializableException: org.apache.spark.SparkContext
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:760)
  at org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:758)
  at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:60)
  at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
  at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:758)
  at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$submitMissingTasks(DAGScheduler.scala:556)
  at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$submitStage(DAGScheduler.scala:503)
  at org.apache.spark.scheduler.DAGScheduler.processEvent(DAGScheduler.scala:361)
  at org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$run(DAGScheduler.scala:441)
  at org.apache.spark.scheduler.DAGScheduler$$anon$1.run(DAGScheduler.scala:149)
  </code></pre>
  
  <p>Could anyone suggest me what could be the problem and what should be done to overcome this issue?</p>