Also, you might be interested in checking out the Apache Beam, Flink, Spark and Storm projects, a lot of things happening on the front of designing data-intensive distributed systems, hacking a side project in any of these might be a fun learning activity.
https://www.youtube.com/playlist?list=PLm3J0oaFux3aafQm568bl...
MIT OCW has a course on Advanced Data Structures which is just great! You can find the Fall-2017 version of it here:
https://courses.csail.mit.edu/6.851/fall17/
I also started reading the "Streaming Systems" book which is a great reading on distributed data-intensive systems, I recommend it:
https://www.amazon.de/dp/1491983876
Also, you might be interested in checking out the Apache Beam, Flink, Spark and Storm projects, a lot of things happening on the front of designing data-intensive distributed systems, hacking a side project in any of these might be a fun learning activity.
Best of luck!