More than three years in the making, with a concerted effort starting last year, my CPU-time profiler landed in Java with OpenJDK 25. It’s an experimental new profiler/method sampler that helps you find performance issues in your code, having distinct advantages over the current sampler. This is what this week’s and next week’s blog posts are all about. This week, I will cover why we need a new profiler and what information it provides; next week, I’ll cover the technical internals that go beyond what’s written in the JEP. I will quote the JEP 509 quite a lot, thanks to Ron Pressler; it reads like a well-written blog post in and of itself.

Before I show you its details, I want to focus on what the current default method profiler in JFR does: