Can't launch simple Sinatra app using rackup and jRuby (no response from web server)

Question

I\'ve got a Sinatra \"hello world\" app that I am trying to run using jRuby. It works when I run the app, but not when I run rackup. Can anyone tell me what is going on here?

Answer 1

Well, this is hardly sufficient to explain what is going on, but I can make it work if in config.ru I replace

run Sinatra::Application

with

Sinatra::Application.run!

In fact, knowing that makes me even more confused. Some sort of bug in Rack?