A Simple Semi On-Line Algorithm for P2//C_{max} with a Buffer

In this paper, we investigate a semi on-line version of the parallel machine scheduling problem. We are given a buffer of length k which is available to maintain k jobs. The jobs arrive one by one and can be temporarily assigned to the buffer if the buffer is not full. The goal is to assign all jobs to the identical machines such that the makespan is minimized. For two machines, Kellerer et al. (1995) showed that no heuristic for this problem can have a worst-case ratio lower than 43. This paper presents a simple algorithm with worst-case ratio 43 for P2//Cmax with a buffer of length 1.