Useful profilers are capable of accurately tracking program execution and providing sleek visualization, with minimal performance impact. When it comes to Ruby profilers, advanced features such as merging Ruby-level and C-level stacks or recording GC / GVL events would be also wanted.

There were many challenges in implementing these features in Pf2, my experimental Ruby profiler. In this talk, I will visit the internals of CRuby and present the difficulties in creating a profiler for the interpreter.

In this talk, I'll discuss the difficulties of creating a Ruby profiler through exploring the internals of CRuby, and introduce Pf2's design choices to overcome challenges. Let us discuss the future of profiling Ruby!