Presentation: (Really) Understanding Garbage Collection

The more things change, the more they stay the same. It's 2019, and while while Garbage Collection in Java has come a long way since inception, the fundamentals have not changed. In this session, Gil Tene (CTO, Azul Systems) will review and classify the various garbage collectors and collection techniques available in JVMs today. Following a quick overview of common garbage collection techniques including generational, parallel, stop-the-world, incremental, concurrent and mostly-concurrent algorithms, we will define terms and metrics common to all collectors. We will classify each major JVM collector's mechanisms and characteristics and discuss the tradeoffs involved in balancing requirements for responsiveness, throughput, space, and available memory across varying scale levels. We will conclude with some pitfalls, common misconceptions, and "myths" around garbage collection behavior, as well as examples of how some good choices can result in impressive application behavior.