Max Mulatz wants to give this talk

Reactive Ruby: build high performant web apps with JRuby and Ratpack

There may occur situations where Ruby is just not able to perform a task efficiently enough. E.g. a web app may require asynchronous programming and non-blocking IO to have the desired throughput...

Ratpack is a modern Java micro-framework (with obvious similarities to Sinatra), based upon reactive principles. Using JRuby and frameworks like Ratpack, we can make use of all the nice performance and concurrency features of the JVM without having to write a single line of Java or XML.

This talk should give you an introduction and enough base-information to deep dive into these topics yourself if you're curious.