Answer #2 to: http://stackoverflow.com/questions/32492560/celluloid-async-inside-ruby-blocks-does-not-work

stackoverflow-async-every.rb

require 'celluloid/current'

class Indefinite
  include Celluloid

  INTERVAL = 0.5
  ONE_AT_A_TIME = false

  def self.run!
    puts "000a Instantiating."
    indefinite = new
    indefinite.run
    puts "000b Running forever:"
    sleep
  end

  def initialize
    puts "001a Initializing."
    @mutex = Mutex.new if ONE_AT_A_TIME
    @running = false
    puts "001b Interval: #{INTERVAL}"
    every(INTERVAL) { run }
  end

  def run
    puts "002a Running."
    unless ONE_AT_A_TIME && @running
      if ONE_AT_A_TIME
        @mutex.synchronize {
          puts "002b Inside lock."
          @running = true
          on_background
          @running = false
        }
      else
        puts "002b Without lock."
        on_background
      end
    end
  end


  def on_background
    uuid = Celluloid::Internals::UUID.generate
    if ONE_AT_A_TIME
      puts "003a #{uuid}: Running background processor in foreground."
    else
      puts "003a #{uuid}: Running in background"
    end
    sleep(INTERVAL*9)
    puts "003b #{uuid}: Finish running simulated 2 second job"
  end
end

Indefinite.run!
puts "004 End of application."
de@extremist /code/issues/so >> master $ ruby -v
ruby 2.2.1p85 (2015-02-26 revision 49769) [x86_64-linux]