How do I use EM::Synchrony::Multi inside a controller action?

synchrony_multi_example.rb

# So, I have an controller action that makes multiple calls to third-party APIs over http.
# I'd like to parallelize these calls via EventMachine::Synchrony::Multi, but can't figure out how to wire the controller
#
# This works fine from, say, a script on the command line, but not in a controller running on a thin server.
#
# What I was missing: a) rack/fiber_pool, b) we don't need the EM.synchrony block
class DemoController < ApplicationController # or a sinatra app, same result
  # ...
  def evented
    multi = nil
    # EM.synchrony do # <= you don't need this synchrony block
      multi = EventMachine::Synchrony::Multi.new
      # queue up a bunch of hopefully-asynchronous API calls
      5.times do |i|
        multi.add i, EM::HttpRequest.new("http://search.twitter.com/search?q=rails+3&format=json").aget
      end
      multi.perform

    #   EM.stop # causes application to exit if present
    # end # <= just call multi.perform

    # parsing of results omitted...

    render :text => multi.inspect # the multi object has no responses.
  end
end

Did this end up working out for you? It appears it did, but I'm curious if you had any thoughts on it after the fact.

Also, do I have to use Thin?

Thin or rainbows--those are the only two evented ruby webservers.