A very completed introduction about the internal of Apache Spark. Highly recommended!
It is a full day workshop (almost 6 hour long video), so you can use following checkpoint to start with the section you are interested in. The section I find most interesting is to reveal how they won 2014 100TB sorting challenge, watch from 4:49:00 Next Gen Shuffle.
Youtube : Advanced Apache Spark Training - Sameer Farooqui (Databricks)
Slides : Devops Advanced Class
This is the short research I did back to web development course in 2016. It will give you a brief overview how online advertiser track the user and few tips about how can you protect yourself from tracking. Hope you enjoy!