@wojciech_jakubo 

About the first question, driver memory utilization is high and we could see multiple cycles of high utlization. The primary reason behind this is, even if a cluster is idle, driver has to perform multiple operations to keep the cluster active and ready for processing. Some of the activities are

• heart beat messages
• gc
• listening for job requests
• hosting spark ui
• monitoring resources

This happens in intervals and this is the reason behind memory utilization happening in cycles on the driver.