signal_trap.rb

class App
  attr_reader :queue

  def initialize
    @queue = []
  end

  def call
    puts "App PID: #{Process.pid}"
    publish
    subscribe
  end

  private

  def subscribe
    loop do
      puts 'Pop: ' + queue.pop.to_s

      sleep(2)
    end
  end

  def publish
    Thread.new do
      loop do
        number = rand(0..9)
        queue.push(number)
        puts 'Queue: ' + queue.to_s

        sleep(1)
      end
    end
  end
end

app = App.new

Signal.trap('TERM') do
  puts 'Received Signal'
  puts 'Process the remaining messages:'
  app.queue.each { |m| puts m }
  exit
end

app.call