How does a Ruby debugger look and work on the inside? Is it difficult to write a debugger? Hear the full story of supporting Ruby 2.0 straight from the maintainer of the RubyMine debugger. In this session we'll expose debugger internals, including different APIs used by debuggers; review how they evolved; and look at what it takes to keep the performance of a debugged application at a reasonable level. We'll also talk about alternative implementations including JRuby and Rubinius.