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

Increase yarn.nodemanager.resource.memory-mb in yarn-site.xml

With 12g per node you can only launch driver(3g) and 2 executors(11g).

Node1 - driver 3g (+7% overhead)

Node2 - executor1 11g (+7% overhead)

Node3 - executor2 11g (+7% overhead)

now you are requesting for executor3 of 11g and no node has 11g memory available.

for 7% overhead refer spark.yarn.executor.memoryOverhead and spark.yarn.driver.memoryOverhead in https://spark.apache.org/docs/1.2.0/running-on-yarn.html