Updating Gin's profiler for current Java']Java

Genetic improvement is a young and growing field. With much research still to be done, a number of tools to support the research community have emerged, with Gin being one such tool targeted at GI for Java. One core component of Gin is the profiler, which is used to identify 'hot' methods in target applications: methods where the CPU spends most time and so may offer the most fertile sections of code for improvements to run time. Gin's profiler is HPROF, which was included with JDKs up to version 8. HPROF is no longer supported and so needs replaced if Gin is to support later versions of Java. Furthermore, little investigation has been made within the GI community comparing different profiling approaches. With this paper and its associated accepted pull request, we replace Gin's CPU profiler with Java Flight Recorder (JFR) to allow Gin to be applied to current Java code, allowing researchers working in GI with more recent JVMs to easily integrate profiling in their pipeline. We also contribute an experimental comparison of the HPROF and JFR profilers for the JVM.