STRIDING-TYPE GENERATION SCANNING FOR PARALLEL GARBAGE COLLECTION

A multiprocessor, multi-program, stop-the-world garbage collection program is described. The system initially over partitions the root sources, and then iteratively employs static and dynamic work balancing. Garbage collection threads compete dynamically for the initial partitions. Work stealing double-ended queues, where contention is reduced, are described to provide dynamic load balancing among the threads. Contention is resolved by using atomic instructions. The heap is broken into a young and an old generation where parallel semi-space copying is used to collect the young generation and parallel mark-compacting the old generation. The old generation heap is divided into a number of contiguous cards that are partitioned into subsets. The cards are arranged into the subsets so that non-contiguous cards are contained in each subset. Speed and efficiency of collection is enhanced by use of card tables and linking objects, and overflow conditions are efficiently handled by linking using class pointers. The garbage collection termination employs a global status word.