message passing to processes, threads, or any combination is über simple in ruby

a.rb

# it's easy, in ruby, to setup a worker farm that utilizes processes, threads,
# or any combination.  the following code sets up three processes, each with
# three worker threads, and a super simple, message passing api, to send
# messages to any process, which will use one of it's threads to do work
#
#
  slaves = Array.new(3){ Slave.new{ Worker.new }}
  workers = slaves.map(&:object)
  a, b, c = workers

  p '_.pid' => Process.pid
  p 'a.pid' => a.pid 
  p 'b.pid' => b.pid 
  p 'c.pid' => c.pid 

  a.message('hai via a...')
  a.relay('hai via a via b...', b)
  a.relay('hai via a via b via c...', b, c)

  sleep

  output = <<-__

    "_.pid"=>45009}
    {"a.pid"=>45029}
    {"b.pid"=>45030}
    {"c.pid"=>45031}
    45029 - 70299573942200 - hai via a...
    45030 - 70299573562400 - hai via a via b...
    45030 - 70299573942200 - hai via a via b via c...

  __


BEGIN {

  require 'thread'
  require 'rubygems'
  require 'slave'

  class Worker
    attr_accessor :q
    attr_accessor :threads

    def initialize
      @q = Queue.new

      @threads = Array.new(3) do
        Thread.new(@q) do |q|
          Thread.current.abort_on_exception = true

          loop do
            msg = q.pop
            STDERR.puts [Process.pid, Thread.current.object_id, msg].join(' - ')
          end
        end
      end
    end

    def message(msg)
      q.push(msg)
    end

    def relay(msg, *args)
      other = args.shift
      other ? other.message(msg) : message(msg)
    end

    def pid
      Process.pid
    end
  end

}