If you have been a professional java developer for a while you have probably heard statements like "Don't optimize prematurely", "Prove that this is actually faster" and "The compiler is very good at optimization" numerous times, but no one ever tells you how to prove that your code is faster. You might have taken a stab at writing your own benchmarks and received responses like "Benchmarking is hard", "This obscure compiler optimization makes your benchmark invalid" and "Did you consider jvm warmup?".

This talk will provide a practical introduction to JMH - the Java Microbenchmark Harness - an Open JDK project for building, running and analyzing benchmarks written in java or other jvm languages. I will talk about how to get started with JMH to write your own benchmarks , the different features and types of benchmarks that are available and show how JMH solves some of the common gotchas present in java benchmarks.