Abstract
We consider online preemptive scheduling of jobs arriving one by one, to be assigned to two identical machines, with the goal of makespan minimization. We study the effect of selecting the best solution out of two independent solutions constructed in parallel in an online fashion. Two cases are analyzed, where one case is purely online, and in the other one jobs are presented sorted by non-increasing sizes. We show that using two solutions rather than one improves the performance significantly, but that an optimal solution cannot be obtained for any constant number of solutions constructed in parallel. Our algorithms have the best possible competitive ratios out of algorithms for each one of the classes.
Similar content being viewed by others
References
Albers, S. (1999). Better bounds for online scheduling. SIAM Journal on Computing, 29(2), 459–473.
Albers, S., & Hellwig, M. (2012). Semi-online scheduling revisited. Theoretical Computer Science, 443, 1–9.
Albers, S., & Hellwig, M. (2017). On the value of job migration in online makespan minimization. Algorithmica, 79(2), 598–623.
Albers, S., & Hellwig, M. (2017). Online makespan minimization with parallel schedules. Algorithmica, 78(2), 492–520.
Aspnes, J., Azar, Y., Fiat, A., Plotkin, S. A., & Waarts, O. (1997). On-line routing of virtual circuits with applications to load balancing and machine scheduling. Journal of the ACM, 44(3), 486–504.
Azar, Y., & Regev, O. (2001). On-line bin-stretching. Theoretical Computer Science, 268(1), 17–41.
Berman, P., Charikar, M., & Karpinski, M. (2000). On-line load balancing for related machines. Journal of Algorithms, 35(1), 108–121.
Böckenhauer, H., Komm, D., Královic, R., Královic, R., & Mömke, T. (2017). Online algorithms with advice: The tape model. Information and Computation, 254, 59–83.
Boyar, J., Favrholdt, L. M., Kudahl, C., Larsen, K. S., & Mikkelsen, J. W. (2017). Online algorithms with advice: A survey. ACM Computing Surveys, 50(2), 19:1-19:34.
Boyar, J., Favrholdt, L. M., Kudahl, C., & Mikkelsen, J. W. (2018). Weighted online problems with advice. Theory of Computing Systems, 62(6), 1443–1469.
Chen, B., van Vliet, A., & Woeginger, G. J. (1995). An optimal algorithm for preemptive on-line scheduling. Operations Research Letters, 18(3), 127–131.
Chen, X., Lan, Y., Benko, A., Dósa, G., & Han, X. (2011). Optimal algorithms for online scheduling with bounded rearrangement at the end. Theoretical Computer Science, 412(45), 6269–6278.
Cheng, T. C. E., Kellerer, H., & Kotov, V. (2012). Algorithms better than LPT for semi-online scheduling with decreasing processing times. Operations Research Letters, 40(5), 349–352.
Dohrau, J. (2015). Online makespan scheduling with sublinear advice. In Proceedings of the 41st international conference on current trends in theory and practice of computer science (SOFSEM’15), pp. 177–188.
Ebenlendr, T., Jawor, W., & Sgall, J. (2009). Preemptive online scheduling: Optimal algorithms for all speeds. Algorithmica, 53(4), 504–522.
Ebenlendr, T., & Sgall, J. (2009). Optimal and online preemptive scheduling on uniformly related machines. Journal of Scheduling, 12(5), 517–527.
Ebenlendr, T., & Sgall, J. (2011). Semi-online preemptive scheduling: One algorithm for all variants. Theory of Computing Systems, 48(3), 577–613.
Epstein, L. (2001). Optimal preemptive on-line scheduling on uniform processors with non-decreasing speed ratios. Operations Research Letters, 29(2), 93–98.
Epstein, L. (2003). Bin stretching revisited. Acta Informatica, 39(2), 97–117.
Epstein, L., & Favrholdt, L. M. (2002). Optimal preemptive semi-online scheduling to minimize makespan on two related machines. Operetions Research Letters, 30(4), 269–275.
Epstein, L., & Favrholdt, L. M. (2005). Optimal non-preemptive semi-online scheduling on two related machines. Journal of Algorithms, 57(1), 49–73.
Epstein, L., & Levin, A. (2014). Robust algorithms for preemptive scheduling. Algorithmica, 69(1), 26–57.
Epstein, L., Noga, J., Seiden, S. S., Sgall, J., & Woeginger, G. J. (2001). Randomized online scheduling on two uniform machines. Journal of Scheduling, 4(2), 71–92.
Faigle, U., Kern, W., & Turán, G. (1989). On the performance of online algorithms for partition problems. Acta Cybernetica, 9(2), 107–119.
Fekete, S.P., Grosse-Holz, J., Keldenich, P., & Schmidt, A. (2019). Parallel online algorithms for the bin packing problem. In Proceedings of the 17th workshop on approximation and online algorithms (WAOA’19), pp. 106–119.
Fleischer, R., & Wahl, M. (2000). Online scheduling revisited. Journal of Scheduling, 3(6), 343–353.
Graham, R. L. (1966). Bounds for certain multiprocessing anomalies. Bell System Technical Journal, 45(9), 1563–1581.
Graham, R. L. (1969). Bounds on multiprocessing timing anomalies. SIAM Journal of Applied Mathematics, 17(2), 416–429.
Jeż, Ł, Schwartz, J., Sgall, J., & Békési, J. (2013). Lower bounds for online makespan minimization on a small number of related machines. Journal of Scheduling, 16(5), 539–547.
Kellerer, H., & Kotov, V. (2013). An efficient algorithm for bin stretching. Operations Research Letters, 41(4), 343–346.
Kellerer, H., Kotov, V., & Gabay, M. (2015). An efficient algorithm for semi-online multiprocessor scheduling with given total processing time. Journal of Scheduling, 18(6), 623–630.
Kellerer, H., Kotov, V., Speranza, M. G., & Tuza, Z. (1997). Semi on-line algorithms for the partition problem. Operations Research Letters, 21(5), 235–242.
Kovács, A. (2010). New approximation bounds for LPT scheduling. Algorithmica, 57(2), 413–433.
Levin, A. (2022). Robust algorithms for preemptive scheduling on uniform machines of non-increasing job sizes. Information Processing Letters, 174, 106211.
McNaughton, R. (1959). Scheduling with deadlines and loss functions. Management Science, 6(1), 1–12.
Renault, M. P., Rosén, A., & van Stee, R. (2015). Online algorithms with advice for bin packing and scheduling problems. Theoretical Computer Science, 600, 155–170.
Rudin, J. F., III., & Chandrasekaran, R. (2003). Improved bounds for the online scheduling problem. SIAM Journal on Computing, 32(3), 717–735.
Sanders, P., Sivadasan, N., & Skutella, M. (2009). Online scheduling with bounded migration. Mathematics of Operations Research, 34(2), 481–498.
Seiden, S. S., Sgall, J., & Woeginger, G. J. (2000). Semi-online scheduling with decreasing job sizes. Operations Research Letters, 27(5), 215–221.
Sgall, J. (1997). A lower bound for randomized on-line multiprocessor scheduling. Information Processing Letters, 63(1), 51–55.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Epstein, L. Parallel solutions for preemptive makespan scheduling on two identical machines. J Sched 26, 61–76 (2023). https://doi.org/10.1007/s10951-022-00764-4
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10951-022-00764-4