Incremental distributed garbage collection using reverse reference tracking

Most modern middleware systems like Java Beans and .NET provide automatic garbage collection (GC). In spite of the many distributed solutions proposed in literature collection is typically limited to a single node and simple leasing techniques are used for remote references. In this paper we present a new incremental multistage GC. It has been implemented in the Plurix operating system but might easily be applied to other platforms. The scheme works incrementally and avoids blocking remote nodes. The reverse reference tracking scheme efficiently detects acyclic garbage and is also used for finding cyclic garbage without precomputing a global root set. To minimize network communication cycle detection splits into a local and a global detection part. Keeping the object markers in a separate stack avoids invalidation of replicated objects. Performance measurements show that the proposed distributed GC scheme scales very nicely.