How the HotSpot and Graal JVMs execute Java Code

What is the work you're doing today?

I work at Morgan Stanley as a Java developer and architect. My main work is around APIs and API gateways. That includes working on architectural components like our cloud strategy, building API infrastructure and all kinds of Java related projects along the way. Besides focusing on the architecture side of things I'm still actively involved in writing code, building gateways in Java using Spring Cloud Gateway and previous Apache Camel.

What are your goals for the talk?

I've been working on a talk which I started four or five years ago when I was teaching graduate students with Ben Evans around what happens with Java code and what happens within the Java virtual machine. Initially, it was exploratory learning for myself, I’m a big believer that to teach something you have to really understand it. As it evolved into more of a complete talk, I started to build more demos and examples to learn about more things myself. It was also where the idea for what eventually became the book Optimizing Java was coined.

What do you want people to leave the talk with?

James Key takeaways would be understanding of Java as a platform and how developers can explore this themselves. I want people to understand how the JVM works, the different subsystems work along the way, and to get an introduction and an understanding to JIT compilation and the differences between Hotspot and Graal.