A Multithreaded Concurrent Garbage Collector Parallelizing the New Instruction in Java

1 Parallel, multithreaded Java applications such as web servers, database servers, and scientific applications are becoming increasingly prevalent. Most of them have high object instantiation rates through the new bytecode that is implemented in a garbage collection subsystem typically. For aforementioned applications, traditional garbage collectors are often the bottleneck that limits program performance and processor utilization on multiprocessor systems. They suffer from long garbage collection pauses (stop-the-world mark-sweep algorithm) or inability of collecting cyclic garbage (reference counting approach). Generational garbage collection, however, is based only on the weak generational hypothesis that most objects die young. In this paper, a new multithreaded concurrent generational garbage collector (MCGC) based on mark-sweep with the assistance of reference counting is proposed. The MCGC can take advantage of multiple CPUs in an SMP system and the merits of light weight processes. Furthermore, the long garbage collection pause can be reduced and the garbage collection efficiency can be enhanced.