In this talk, you will learn about the surprises that an experienced JVM engineer gets when doing Java development in the wild. Bengt worked for 10 years with the Java platform specialising in garbage collection implementations inside the JVM. He worked with both the JRockit and HotSpot Java virtual machines and has built JVMs for JDK 6, JDK 7, JDK 8 and JDK 9. Two years ago he moved over to using the Java platform as a developer by joining the software team at Looklet. There are many assumptions you make as a JVM engineer that turn out to be quite wrong when you end up being a user of the platform rather than a developer of the platform. And there are many things you never even thought about as a JVM developer.