Semi-online hierarchical scheduling problems with buffer or rearrangements

  • Authors:

  • Xin Chen;Zhenzhen Xu;GyöRgy DóSa;Xin Han;He Jiang

  • Affiliations:

  • Software School, Dalian University of Technology, China;Software School, Dalian University of Technology, China;Department of Mathematics, University of Pannonia, Veszprém, Hungary;Software School, Dalian University of Technology, China;Software School, Dalian University of Technology, China

  • Venue:
  • Information Processing Letters
  • Year:
  • 2013

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Abstract

In this paper, we consider semi-online hierarchical scheduling problems on two identical machines, with the purpose of minimizing the makespan. The first investigated problem is the buffer version, where a buffer of a fixed capacity K is available for storing at most K jobs. When the current job is given, we are allowed to assign it on some machine irrecoverably; or temporarily store it in the buffer. But in the latter case if the buffer was full then an earlier job is removed from the buffer and assigned it to some machine. The second one is a reassignment version, where when the input is end, we are allowed to reassign at most K jobs. For both versions, we show no online algorithm can have a competitive ratio less than 32, then propose two online algorithms with a competitive ratio 32 with K=1 for both versions of the problem, i.e., using only buffer of size one, or using only one rearrangement at the end.