using spark 2.0.2  and while running sample streaming app with kinesis
noticed (in admin ui Storage tab)  "Stream Blocks" for each worker keeps climbing up

then also (on same ui page) in Blocks section I see blocks such as below


that are marked as Memory Serialized 

that do not seem to be "released"

above eventually consumes executor memories leading to out of memory exception on some 

is there a way to "release" these blocks free them up , app is sample m/r 

I attempted rdd.unpersist(false) in the code but that did not lead to memory free up

thanks much in advance!