Garbage Collection in an Embedded Java Virtual Machine

Abstract

Garbage collection in the Java virtual machine is a core component that relieves application programmers of difficulties related to memory man-agement. It should also take into account the characteristics of embedded envi-ronments. In this paper, we propose a garbage collector that meets the require-ments for embedded environments. The proposed garbage collector is primarily based on generational garbage collection where a heap is composed of young and old generations. A semi-space copying collector is employed for a young generation, and an incremental copying collector is employed for an old genera-tion. Owing to its contiguous allocations, the proposed method provides fast al-locations and the locality of references. By adjusting the size of a young genera-tion, the block size, and the number of blocks in a frame, it is able to control the delay time caused by garbage collection, and thus guarantee the real time con-straints. Also, it employs a novel write barrier mechanism for efficiently deter-mining reachable objects in a specific frame. With all these characteristics to-gether, the proposed garbage collector can reclaim all the garbage objects precisely as well as timely. To reveal its superiority, we perform a series of ex-periments.