Profiling + Indy

[Charles Oliver Nutter]

I'm looking to get back into JRuby + Indy work now that the heaviest
conferences are behind me. Part of this involves running larger
benchmarks where the hot spots may not be apparent at a glance. In
order to investigate performance on such benchmarks, I will want to do
some profiling. But what should I use?

For really egregious problems, the sampling profiler (-Xprof) "sort
of" works. It's grossly inaccurate when there's no stand-out hotspot,
but if something is incredibly bad it usually shows it. So that's
option 1.

There's -Xrunhprof:cpu=times, which is more accurate, but the impact
to running code is enormous, there's no way to filter out
uninteresting code (like JDK core), and I have no idea if it works
properly with indy (given that there's ongoing work to make JVMTI +
indy play nice). That's option 2.

Are either of these options any good? What else do you recommend?

- Charlie