Design and Implementation of Efficient Cycle Detectors for Reference Counting Systems

• Main Authors: Yeh-Young Hou, 侯曄暘
• Other Authors: Ting-Wei Hou
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/55141529383539377679

碩士 === 國立成功大學 === 工程科學系碩博士班 === 94 === In garbage collection systems, reference counting technique can not reclaim cyclic garbage. It is often complemented by a cycle detector. In this thesis, we first try to improve the LW-CRC (Lightweight Cyclic Reference Counting) algorithm proposed by Lin-Hou. The original LW-CRC algorithm is a practical approach. However, there exist few cases that can not be properly handled in theory. The algorithms proposed herein relieve such a problem without affecting the practicality, where more cyclic garbage can be collected. In addition, we develop a new cycle collection algorithm based on finding strongly connected components (SCC), denoted SCC-CRC. It is a complete algorithm and it has good performance. The main idea of the proposed algorithms is to reduce the number of traces over objects. Compare with the tri-color algorithm, a well-known cycle collection algorithm, our algorithms reduce the time complexity from O(2n) ~ O(3n) to O(n) ~ O(2n). We implemented the algorithms on Jikes RVM (Research Java Virtual Machine), and used SPECjvm 98 as the benchmark programs. The experimental results demonstrate that the proposed algorithms are more practical and efficient, compared to the tri-color algorithm.