Java VisualVM giving bizarre results for CPU profiling - Has anyone else run into this?

Question

I have written this small (and brutally inefficient) class and wanted to profile it using the Java VisualVM.

public class Test {

    public static void main         


        

Answer 1

jvisualvm profiling probably weaves bytecode into classes as they are loaded. Since your program has just one class and it is already initialized by the time jvisualvm arrives on the scene, I would suppose it cannot be instrumented.

Move your fib method into another class and try profiling again. You might add a jvm option "-verbose:class" to double check that the class isn't loaded before you enable cpu profiling in jvisualvm.

Edit: Thanks JB for the comment. Forget my classloading hogwash. My intuition is that the fib method is too tightly coupled to the main method, so it is effectively bytecode currently being executed.