Design of a Generic and Reusable Scheduler for Smalltalk-80 Position Paper Presented at the Ecoop'92 Workshop on Object-Based Concurrency and Reuse

This paper discusses the reuse of software components for describing and implementing various schedulers. We advocate the design of a generic and general purpose scheduler. This generic scheduler is based on object-oriented methodology (namely Smalltalk-80) and may be instantiated to match various scheduling strategies. This scheduler has been primarily developed for Actalk, a testbed for actor languages integrated into Smalltalk-80, to ease the prototyping of scheduling policies for actors. Our generic scheduler is particularly e cient to help the design of time-sharing algorithms that are not supported by the standard Smalltalk-80 scheduler. Our starting point was the Smalltalk-80 scheduler. We extend it to take time-sharing into account. In spite of the fact that our generic scheduler is used for Actalk, its purpose is far more general: it may be used for simulation for example. In this paper, we rstly present the goal of time-sharing algorithms and a few examples. Secondly, we explain why and how we designed our own generic scheduler on top of the Smalltalk-80 one. We illustrate the use of our scheduler by simulating the algorithms rstly presented as examples. We discuss how object-oriented techniques allow us to build-up and reuse scheduling policies.