def process_cpu_times(&callback)
      determine_cpu_times = Proc.new do
        ::Process.times.to_a rescue [nil, nil, nil, nil]
      end
      EM::defer(determine_cpu_times, callback)
    end
def process_cpu_times(&callback)
      determine_cpu_times = Proc.new do
        ::Process.times.to_a rescue [nil, nil, nil, nil]
      end
      EM::defer(determine_cpu_times, callback)
    end
Retrieve the process CPU times. If the cpu times cannot be
 determined and an error is thrown, `[nil, nil, nil, nil]` will
 be returned.

 @return [Array] CPU times: utime, stime, cutime, cstime