Worker Threads Vs Spark Executor Memory

[Annamalai, Sai IN BLR STS]

Hi All,

1)      Does number of worker threads bear any relationship to setting executor 
memory ?.
 I have a 16 GB RAM, with an 8-core processor. I had set SPARK_MEM to 12g and 
was running locally with default 1 thread.
So this means there can be maximum one executor in one node scheduled at any 
point of time.
If I increase the number of worker threads to say 4, do I need to reduce 
SPARK_MEM to 3g or I need not ???
2)      Is there any performance difference between running in interactive 
spark shell to non-interactive standalone spark apart from building 
time(sbt...) ???


Thanks !!