em-http callbacks not being given time to fire when inside an async callback that is repeatedly triggered?

gistfile1.rb

require 'amqp'
require 'em-http-request'

EM.run do
  connection = AMQP.connect(:host => '127.0.0.1')
  channel  = AMQP::Channel.new(connection)
  queue    = channel.queue("em.load.test", :auto_delete => true)
  exchange = channel.default_exchange

  def handle_message(header, payload, *args)

    puts "got message: #{payload}"

    # call out to a goliath server to get some data based on the incoming message
    url = "http://localhost:9000/get_data/#{payload}"

    http = EM::HttpRequest.new(url).get

    http.callback do
      puts "got a response: #{http.response}"
    end

    http.errback do
      puts "an error occurred in the http request!"
    end

  end

  queue.subscribe(&method(:handle_message))

  10000.times do |i|
    exchange.publish "#{i}", :routing_key => queue.name
  end
end