A distributed garbage collector for active objects

Abstract

This paper presents an algorithm that performs garbage collection in distributed systems of active objects (i.e., objects having their own threads of control). Our proposition extends the basic marking algorithm proposed by Kafura in [1] to a distributed environment. The proposed garbage collector is made up of a set of local garbage collectors, one per site, loosely coupled to a (logically centralized) global garbage collector that maintains a global snapshot of the system state relevant to garbage collection. The specific features of the proposed garbage collector are that local garbage collectors need not be synchronized with each other for detecting garbage objects, and that faulty sites and communication channels are tolerated. The paper describes the proposed garbage collector, together with its implementation and performance for a concurrent object-oriented language running on a local area network of workstations.