Parallel requests in sinatra

app.rb

require "sinatra"
require "sinatra/async"
require "em-synchrony"
require "em-synchrony/em-http"

class App < Sinatra::Base
  register Sinatra::Async

  aget "/" do
    Fiber.new {
      urls = %w(http://bbc.com http://google.com)
      results = EM::Synchrony::Iterator.new(urls, 2).map do |url, iter|
        http = EventMachine::HttpRequest.new(url).aget
        http.callback { iter.return(http) }
        http.errback { iter.return(http) }
      end

      body { results.map(&:state).inspect }
    }.resume
  end
end