Phusion Passenger + Workling + RabbitMQ

Question

I am trying to deploy a RoR app that does some asynchronous task. I use workling for that and the message queue is RabbitMQ. This combination worked flawlessly with Starling but we decided to change the MQ for Rabbit. I read somewhere that I should include the following code in my environment.rb

require 'mq' 
if defined?(PhusionPassenger) 
  PhusionPassenger.on_event(:starting_worker_process) do |forked| 
    if forked 
      if EM.reactor_running? 
        EM.stop_event_loop 
        EM.release_machine 
        EM.instance_variable_set( '@reactor_running', false ) 
      end 
      Thread.current[:mq] = nil 
      AMQP.instance_variable_set('@conn', nil) 
    end 
    th = Thread.current 
    Thread.new{ 
      AMQP.connect(:host => 'localhost'){ 
        th.wakeup 
      } 
    } 
    Thread.stop 
  end 
end 

But that now Apache fails completely with message: The server encountered an internal error or misconfiguration and was unable to complete your request

Answer 1

EDIT: I've improved the code below somewhat since posting this. Available here: http://www.hiringthing.com/2011/11/04/eventmachine-with-rails.html

I just spent a milliioon years trying to get this to work, and finally did. Here is my code:

require 'amqp'
module HiringThingEM
  def self.start
    if defined?(PhusionPassenger)
      PhusionPassenger.on_event(:starting_worker_process) do |forked|
      if forked && EM.reactor_running?
          EM.stop
      end
      Thread.new {
      EM.run do
         AMQP.channel ||= AMQP::Channel.new(AMQP.connect(:host=> Q_SERVER, :user=> Q_USER, :pass => Q_PASS, :vhost => Q_VHOST ))
      end
      }
      die_gracefully_on_signal
      end
    end
  end

  def self.die_gracefully_on_signal
    Signal.trap("INT")  { EM.stop }
    Signal.trap("TERM") { EM.stop }
  end
end

HiringThingEM.start

Now I can use:

EM.next_tick { AMQP.channel.queue(Q_Q).publish("hi mom") }

Inside the controllers of my Rails app.

Hope this helps someone.

Answer 2

Not really an answer, but unless you're committed to AMQP, I would recommend using https://github.com/defunkt/resque - it does the asynchronous job + fork gig very nicely.