Using Multiple Servers in Concurrent Garbage Collector.

Abstract

Object-oriented programming languages are being widely adopted as one of the most powerful languages due their flexibility and reusability. However, these languages suffer from memory mismanagement that could be critical especially in real-time and embedded systems. Automatic memory management through garbage collector handles this problem. Concurrent garbage collection based on sporadic or deferrable server is considered the most famous collectors in this area. In such algorithms, the garbage collection task is assumed to be the single aperiodic task in the system. When there are other different types of traffic, with short deadlines and long deadlines, the single server provides poor performance. The garbage collection task may have to wait till a less urgent or a higher deadline request finishes its execution that leads to an increase in the system memory requirement and perhaps a deadline miss of the garbage collection thread. This paper concentrates on minimizing the system memory requirement when there are multiple sources of events by introducing a new concurrent garbage collector. In the proposed collector, the system will have multiple servers; rather than one as in the available garbage collectors. These servers can either share or not share their capacities, i.e. a server can use the unused capacity of other servers in case of sharing. The two schemes give preference to higher priority servers. We also propose a modification in the copying collector that enhances its performance. The simulation results show that using multiple servers with capacity sharing in garbage collection scheduling strategy exhibits a better performance in terms of reducing the system memory requirement and meeting most of deadlines than using either single server or multiple servers without capacity sharing collectors. However, the capacity-sharing scheme gave lower response times for jobs with short deadlines, like GC task, than without capacity sharing scheme.