Browsing by Author "Washabaugh, Douglas M."

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    Distributed Garbage Collection of Active Objects
    Washabaugh, Douglas M.; Kafura, Dennis G. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1990)
    This paper shows how to perform distributed automatic garbage collection of objects possessing their own thread of control. The relevance of garbage collection and concurrent objects used in the paper is explained. The collector is comprised of a collection of independent local collectors, one per node, loosely coupled to a distributed global collector. The mutator (application), the local collectors and the global collector run concurrently. The synchronization necessary to achieve correct and efficient concurrent operation between the collectors and the mutator is presented in detail. An interesting aspect of the distributed collector is the termination algorithm: the collector algorithm running on one node, which considers itself to be "done," may become "undone" by the action of a collector algorithm on another node.
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    Garbage Collection of Actors
    Kafura, Dennis G.; Washabaugh, Douglas M.; Nelson, Jeff (Department of Computer Science, Virginia Polytechnic Institute & State University, 1990)
    This paper considers the garbage collection of concurrent objects for which it is necessary to know not only "reachability", the usual criterion for reclaiming data, but also the "state" (active or blocked) of the object. For the actor model, a more comprehensive definition than previously available is given for reclaimable actors. Two garbage collection algorithms, implementing a set of "coloring" rules, are presented and their computational complexity is analyzed. Extensions are briefly described to allow incremental, concurrent, distributed and real-time collection. It is argued that the techniques used for the actor model applies to other object-oriented concurrent models.
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    Real-Time Garbage Collection of Actors
    Washabaugh, Douglas M.; Kafura, Dennis G. (Department of Computer Science, Virginia Polytechnic Institute & State University, 1990)
    This paper shows how to perform real-time automatic garbage collection of objects possessing their own thread of control. Beyond its interest as a novel real-time problem, the relevance of automatic management and concurrent objects to real-time applications is briefly discussed. The specific model of concurrent objects used in the paper is explained. A definition of real-time garbage collection is given and an algorithm satisfying this definition is described. An analysis of the relationship between latency, memory overhead and system size shows that this approach is immediately feasible for low-performance real-time systems or multi-processor real-time systems with dedicated processor functions. Future improvements in the collector's performance are outlined.