Slides: https://www.slideshare.net/DataStax/lessons-learned-on-java-tuning-for-our-cassandra-clusters-carlos-monroy-knewton-c-summit-2016 | Customizing JVM settings for the needs of an application can be a tricky business, especially when running externally developed software such as Cassandra. In this talk I will share our experiences and the procedure that we have used to test and validate changes with Java tuning. We'll explore with two recent experiences: changes and monitoring of G1 garbage collection, and moving buffer objects off the heap. For the talk, I'll discuss our tuning process at Knewton. I will share some of the challenges that we faced while identifying what we expected to learn. I'll discuss how we isolated and minimized variables across tests, the importance of the duration of these tests, and how we try to separate correlation from causation. I will demonstrate how to use and interpret the results of the custom scripts that we were driven to develop to gain visibility into our G1GC processes; these scripts will be open sourced. About the Speaker Carlos Monroy Senior Software Engineer, Knewton Carlos Monroy is a senior engineer on the database team at Knewton, an education company that created an adaptive learning platform. Carlos has been developing software professionally since 1998. His experience holding multiple roles on the software lifecycle provides him a wholistic approach. Having used over a half dozen relational database engines, he has recently come over to the NoSQL side, first working with HBase and for the last three years Cassandra.