Wait, what about stackprof rb-lineprof flamegraph rack-mini-profiler

My theory is that it takes both a certain amount of pressure to create those tools, a certain amount of expertise and a certain amount of tooling available from the language. Due to being old, Perl has all of these and in Devel::NYTProf has a more than excellent profiler that goes beyond line, into statement level. See for example these profiling runs created with it: https://dl.dropboxusercontent.com/u/10190786/ppi_bench.zip

>Why is line level profiling so non-existent for dynamic languages?

It isn't. As usual the answer is LuaJIT (sorry, I am a fanboy, got to admit it): http://permalink.gmane.org/gmane.comp.lang.lua.luajit/3413

I was just looking at phpdbg and xdebug yesterday, and they do it, iirc :) so, not impossible, but Ruby does do more stuff dynamically.