[spark-src-core] 2.4 communications b/t certain kernal components

1  data flow overview

 note:

-arrow here is means by:bold line is as data line ‘w/o sender and recevier meanings’ but only with data ‘from-to’

-two ways to retieve task result:direct result and  indirect result(over akka frame size)

 

2.actor in spark

 3.several components communicated through EndpointRef