Replication-based incremental copying collection

Abstract

We introduce a new replicationbased copying garbage collection technique. We have implemented one simple variation of this method to provide incremental garbage collection on stock hardware with no special operating system or virtual memory support. The performance of the prototype implementation is excellent: major garbage collection pauses are completely eliminated with only a slight increase in minor collection pause times.

Unlike the standard copying algorithm, the replication-based method does not destroy the original replica when a copy is created. Instead, multiple copies may exist, and various standard strategies for maintaining consistency may be applied. In our implementation for Standard ML of New Jersey, the mutator continues to use the from-space replicas until the collector has achieved a consistent replica of all live data in to-space.

We present a design for a concurrent garbage collector using the replication-based technique. We also expect replication-based gc methods to be useful in providing services for persistence and distribution, and briefly discuss these possibilities.

This research was sponsored by the Avionics Lab, Wright Research and Development Center, Aeronautical Systems Division (AFSC), U. S. Air Force, Wright-Patterson AFB, OH 45433-6543 under Contract F33615-90-C-1465, Arpa Order No. 7597 and by the Air Force Systems Command and the Defense Advanced Research Projects Agency (DARPA) under Contract F19628-91-C-0128.

The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the U.S. Government.