Apache Spark: setting executor instances does not change the executors

Question

I have an Apache Spark application running on a YARN cluster (spark has 3 nodes on this cluster) on cluster mode.

When the application is running the Spark-UI shows

Answer 1

You only have 3 nodes in the cluster, and one will be used as the driver, you have only 2 nodes left, how can you create 6 executors?

I think you confused --num-executors with --executor-cores.

To increase concurrency, you need more cores, you want to utilize all the CPUs in your cluster.