title: How Spark RDD partitions are processed if no. of executors < no. of RDD partition
body: <p>I want to understand a basic thing in spark streaming. I have 50 Kafka topic partitions and 5 numbers of executors, I am using DirectAPI so no. of RDD partitions will be 50. How this partition will be processed on 5 executors? Will spark process 1 partition at a time on each executors or if the executor has enough memory and cores it will process more than 1 partition in parallel on each executor.</p>