SparkR Error in if (returnStatus !=0) - r

Question

I have setup a spark cluster on EC2 with 20 nodes and set all the node IPs in conf/slaves of the master and launched a job with SparkR and 50 slices. My nodes are dual core with 4GB memory and at the end of my job collect the results into a csv file which should contain about 15000 lines (and 7 columns with floats). The job runs fine for a while (6000s) until I get the following error from the master (this is not from the spakr master log, but from the terminal window where I execute the spark job):
16/03/21 22:39:31 INFO TaskSetManager: Finished task 27.0 in stage 0.0 (TID 27) in 5954810 ms on ip-xxx-yy-xx-zzz.somewhere.compute.internal (8/40)
16/03/21 22:39:38 INFO TaskSetManager: Finished task 12.0 in stage 0.0 (TID 12) in 5962190 ms on ip-xxx-xx-xx-xxx.somewhere.compute.internal (9/40)
Error in if (returnStatus != 0) { : argument is of length zero
Calls: <Anonymous> -> <Anonymous> -> .local -> callJMethod -> invokeJava
Execution halted
16/03/21 22:40:16 INFO SparkContext: Invoking stop() from shutdown hook
16/03/21 22:40:16 INFO SparkUI: Stopped Spark web UI at http://172.31.21.134:4040
16/03/21 22:40:16 INFO DAGScheduler: Job 0 failed: collect at NativeMethodAccessorImpl.java:-2, took 6001.135894 s
16/03/21 22:40:16 INFO DAGScheduler: ShuffleMapStage 0 (RDD at RRDD.scala:36) failed in 6000.500 s
16/03/21 22:40:16 ERROR RBackendHandler: collect on 16 failed
16/03/21 22:40:16 ERROR LiveListenerBus: SparkListenerBus has already stopped! Dropping event SparkListenerStageCompleted(org.apache.spark.scheduler.StageInfo#6c9d21b2)
16/03/21 22:40:16 ERROR LiveListenerBus: SparkListenerBus has already stopped! Dropping event SparkListenerJobEnd(0,1458600016592,JobFailed(org.apache.spark.SparkException: Job 0 cancelled because SparkContext was shut down))
16/03/21 22:40:16 INFO SparkDeploySchedulerBackend: Shutting down all executors
I checked in the worker logs and I see the following two lines at the end of the log file:
16/03/21 22:40:16 INFO CoarseGrainedExecutorBackend: Driver commanded
a shutdown 16/03/21 22:40:16 ERROR CoarseGrainedExecutorBackend:
RECEIVED SIGNAL 15: SIGTERM
and then the log stops abruptly (no other errors or warnings before).
I don't see any hint towards what could cause the crash in the log file, my only guess is that it could be an out-of-memory error because when I run on a reduced input dataset it runs fine. Am I missing something?