NullPointerException

[Saurabh Guru]

I am seeing the following exception in my Spark Cluster every few days in 
production.

2016-03-12 05:30:00,541 - WARN  TaskSetManager - Lost task 0.0 in stage 12528.0 
(TID 18792, ip-1X-1XX-1-1XX.us 
<http://ip-10-180-1-188.us/>-west-1.compute.internal
): java.lang.NullPointerException
       at 
org.apache.spark.util.collection.ExternalSorter.insertAll(ExternalSorter.scala:192)
       at 
org.apache.spark.shuffle.sort.SortShuffleWriter.write(SortShuffleWriter.scala:64)
       at 
org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:73)
       at 
org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
       at org.apache.spark.scheduler.Task.run(Task.scala:89)
       at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
       at 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
       at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
       at java.lang.Thread.run(Thread.java:745)


I have debugged in local machine but haven’t been able to pin point the cause 
of the error. Anyone knows why this might occur? Any suggestions? 


Thanks,
Saurabh