How to set amount of Spark executors?

Question

How could I configure from Java (or Scala) code amount of executors having SparkConfig and SparkContext? I see constantly 2 executors. Looks like

Answer 1

OK, got it. Number of executors is not actually Spark property itself but rather driver used to place job on YARN. So as I'm using SparkSubmit class as driver and it has appropriate --num-executors parameter which is exactly what I need.

UPDATE:

For some jobs I don't follow SparkSubmit approach anymore. I cannot do it primarily for applications where Spark job is only one of application component (and is even optional). For these cases I use spark-defaults.conf attached to cluster configuration and spark.executor.instances property inside it. This approach is much more universal allowing me to balance resources properly depending on cluster (developer workstation, staging, production).