signal_exception.rb

class App
  attr_reader :queue
  
  def initialize
    @queue = []
  end
  
  def call
    puts "App PID: #{Process.pid}"
    publish
    subscribe
  rescue SignalException => e
    puts "Received Signal #{e}"
    puts 'Process the remaining messages:'
    queue.each { |m| puts m }
    exit
  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.new.call