A two-stage M/G/1 queue with discretionary priority

In this paper, we study a two-stage M/G/1 queue with discretionary priority. We construct an imbedded Markov model for specific time points on the time axis. By investigating the embedded Markov chain, the marginal queue length distribution, mean queue length and mean waiting time can be figured out. As the special cases, the exponential, constant and triangular service times are considered.