Sample Asynchronous action code for rails

async_controller.rb

# FROM: http://www.jonb.org/2013/01/25/async-rails.html @jbaudanza
# Modified to get it working.

module AsyncController

  # This is the rack endpoint that will be invoked asyncronously. It will be
  # wrapped in all the middleware that a normal Rails endpoint would have.
  class RackEndpoint
    attr_accessor :action

    def call(env)
      @action.call(env)
    end
  end

  module ClassMethods
    def prepareAsyncMiddleware!
      @endpoint = RackEndpoint.new

      # LocalCache isn't able to be instantiated twice, so it must be removed
      # from the new middleware stack.
      middlewares = Rails.application.middleware.middlewares.reject do |m|
        reject = false
        reject = true if m.klass.name == "ActiveSupport::Cache::Strategy::LocalCache"
        reject
      end
      @wrapped_endpoint = middlewares.reverse.inject(@endpoint) do |a, e|
        e.build(a)
      end
    end
    def asyncMiddleware=(newM)
      @wrapped_endpoint = newM
    end
    def asyncMiddleware
      @wrapped_endpoint
    end
    def asyncActionEndpoint
      @endpoint
    end
    def asyncActionEndpoint=(newAE)
      @endpoint = newAE
    end
  end

  def self.included(mod)
    mod.extend(ClassMethods)
    mod.prepareAsyncMiddleware!
  end

  # Called to finish an asynchronous request. Can be invoked with a block
  # or with the symbol of an action name.
  def finish_request(action_name=nil, &proc)
    async_callback = request.env.delete('async.callback')
    env = request.env.clone

    if !action_name
      env['async_controller.proc'] = proc
      action_name = :_async_action
    end

    self.class.asyncActionEndpoint.action = self.class.action(action_name)

    begin
      async_callback.call(self.class.asyncMiddleware.call(env))
    rescue Exception => e
      # TODO: Should return a crash response
      puts "CRASHED!".white.on_red
      puts e.inspect
    end
  end

  def _async_action
    instance_eval(&request.env['async_controller.proc'])
  end

  def async!
    render :text => "", :status => -1
  end
end

test_controller.rb

# FROM: http://www.jonb.org/2013/01/25/async-rails.html @jbaudanza
# Modified to get it working.

class TestController < ActionController::Base
  include AsyncController

  def bulkdata
    _since = DateTime.strptime(params[:from], '%s')
    _until = DateTime.strptime(params[:to], '%s')

    Thread.new do
      sleep 30

      finish_request do
        render text: "This response has responded 30 seconds later, but the server doesn't get blocked."
      end
    end

    async!
  end

end