A Real-time Extension To The Standard Java Virtual Machine

Programming in Java is attractive for its safety, simplicity, maintainability and portability, but much work is to be performed to apply it into the real-time software development. We try to address the two main issues that, thread scheduling and garbage collection, with real-time concerns. Besides, considering the fact that most real-time applications run in a memory constrained environment, the extra memory requirement caused by the introduction of garbage collection in systems is carefully concerned.Garbage collection is a key feature in the Java virtual machine. But it also brings some obstacles to real-time issues. Previous work had been put on solving the realtime problems of the garbage collector. Among it there are concurrent collectors that can provide truly real-time guarantees but they rely on a relatively large amount of redundant system memory. This thesis concentrates on minimizing the system memory requirement with a new concurrent garbage collector which is based on a deferrable server together with a particular parameter configuration scheme proposed by this thesis.The parameter configuration scheme is addressed using two different approaches, that is, the utilization based analysis and exact analysis of the selection of parameters. In this way, the worst-case response time of a garbage collector is minimized, and so is the worst-case system memory requirement, with the schedulability of tasks with hard time constraint not jeopardized. Furthermore, the simulation results demonstrate that, based on the new algorithm, the actual maximum system memory requirement for a given task set also becomes less than that of any previous concurrent collector.The implementation of a prototype of real-time Java extension is also presented at length, which covers the implementation of real-time threads, real-time scheduling, our concurrent garbage collector, and so on. Correctness verification and initial performance evaluation are also presented. The extension can act as a runtime platform for real-time applications written in Java, and an experimental nursery for testing the feasibility and efficiency, for finding out the advantages or disadvantages of developing real-time software in Java. We think the feedback from the users, i.e. real-time software developers, will be invaluable to further research in the real-time Java field.