Real-time GC in JeRTy/spl trade/VM using the return-barrier method

Runtime systems for applications written in certain languages such as Java/spl trade/ and Lisp usually have a garbage collection (GC) feature to make efficient use of memory. With this feature, the system, before running out of memory space, automatically reclaims unnecessary fragments of memory at one burst and recycles them for use by applications. In conventional implementations, however, the system has to suspend the execution of applications while carrying out GC, which renders GC generally unsuitable for real-time processing systems. As a solution to this problem, Yuasa, et al. of Kyoto University developed the return-barrier method based on snapshot GC. Return-barrier enhances real-time GC processing over the original snapshot GC. Some reports have been published on the evaluation of the return-barrier method in the Lisp environment such as Kyoto Common Lisp (KCL). In this paper, we report the implementation of the return-barrier method for JeRTy/spl trade/VM, which is a real-time environment for embedded Java applications developed by OMRON Corporation, and its performance improvement over the conventional GC in JeRTyVM.