Parcplace Systems

Franklin R Jackson

David M Ungar

Allan M Schiffman

L Peter Deutsch

The primary purpose of an automatic storage-reclamation system for digital computers is to reclaim the memory occupied by memory objects that are no longer necessary for the correct operation of the computer programs that are clients of the reclamation system. Those objects that are unnecessary in this respect are commonly called garbage objects or, more simply, garbage, and the act of reclaiming such objects is commonly called garbage collection. Frequently, however, some final action or sequence of actions needs to be taken when a memory object becomes a garbage object, beyond simply reclaiming the memory occupied by such objects. An automated finalization mechanism performs such a pre-specified set of actions when it has determined that a memory object has become garbage. A postmortem finalization mechanism performs these finalization actions only after the garbage object has actually been reclaimed by the system's garbage collector. Delaying the execution of the finalization actions until the object in question has been fully reclaimed prevents this object from accidentally being resurrected as a possible side effect of the finalization actions. A mechanism for supporting postmortem finalization is constructed by extending the capabilities of an automatic storage-reclamation system.

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Franklin R Jackson