The metronome: A simpler approach to garbage collection in real-time systems

Abstract

With the wide-spread adoption of Java, there is significant interest in using the language for programming real-time systems. The community has generally viewed a truly real-time garbage collector as being impossible to build, and has instead focused its efforts on adding manual memory management mechanisms to Java. Unfortunately, these mechanisms are an awkward fit for the language: they introduce significant run-time overhead, introduce run-time memory access exceptions, and greatly complicate the development of library code. In recent work we have shown that it is possible to build a real-time collector for Java with highly regular CPU utilization and greatly reduced memory footprint. The system currently achieves 6 ms pause times with 50% CPU utilization (MMU) and virtually no "tail" in the distribution. We show how this work can be incorporated into a general real-time framework, and extended to systems with higher task frequencies. We argue that the community should focus more effort on such a simple, orthogonal solution that is true to the spirit of the Java language. © Springer-Verlag Berlin Heidelberg 2003.