class Resque::Worker

def start_heartbeat
  remove_heartbeat
  @heartbeat_thread_signal = Resque::ThreadSignal.new
  @heartbeat_thread = Thread.new do
    loop do
      heartbeat!
      signaled = @heartbeat_thread_signal.wait_for_signal(Resque.heartbeat_interval)
      break if signaled
    end
  end
  @@all_heartbeat_threads << @heartbeat_thread
end