We survey basic garbage collection algorithms, and variations such as incremental and generational collection; we then discuss low-level implementation considerations and the relationships between storage management systems, languages, and compilers. Throughout, we attempt to present a uni ed view based on abstract traversal strategies, addressing issues of conservatism, opportunism, and immediacy of reclamation; we also point outavariety of implementation details that are likely to have a significant impact on performance.

this paper. associated with a relocating collector is saved; other costs remain, however, such as the costs of updating all pointers and foregoing some compiler optimizations.

We survey basic garbage collection algorithms, and variations such as incremental and generational collection; we then discuss low-level implementation considerations and the relationships between storage management systems, languages, and compilers. Throughout, we attempt to present a unified view based on abstract traversal strategies, addressing issues of conservatism, opportunism, and immediacy of reclamation; we also point out a variety of implementation details that are likely to have a significant impact on performance. Contents 1 Automatic Storage Reclamation 2 1.1 Motivation : : : : : : : : : : : : : : : : 2 1.2 The Two-Phase Abstraction : : : : : : : 4 1.3 Object Representations : : : : : : : : : 5 1.4 Overview of the Paper : : : : : : : : : : 5 2 Basic Garbage Collection Techniques 6 2.1 Reference Counting : : : : : : : : : : : : 6 2.1.1 The Problem with Cycles : : : : 7 2.1.2 The Efficiency Problem : : : : : 7 2.1.3 Deferred Reference Counting. : : 8 2.1.4 Variations on R...