Stefan Marr

Associate Professor (Senior Lecturer)
and Royal Society Industry Fellow

Stefan Marr I am working at the School of Computing at the University of Kent. My work focuses on programming language implementation techniques, complex concurrent systems, and tooling.

Much of work revolves around making interpreters faster, detecting and preventing concurrency bugs at run time, and use modern language runtime systems to provide programmers with better tooling.

For contact details see my page at the School of Computing.

Archive of posts with the tag Profilers

Sep 17, 2024: Instrumentation-based Profiling on JVMs is Broken!

Last year, we looked at how well sampling profilers work on top of the JVM. Unfortunately, they suffer from issues such as safepoint bias and may not correctly attribute observed run time to the correct methods because of the complexities introduced by inlining and other compiler optimizations.
Sep 20, 2023: Don't Blindly Trust Your Java Profiler!

How do we know on what to focus our attention when trying to optimize the performance of a program? I suspect at least some of us will reach for sampling profilers. They keep the direct impact on the program execution low, and collect stack traces every so often during the program execution. This gives us an approximate view of where a program spends its time. Though, this approximation as it turns out can be surprisingly unreliable.