The Research For The Critical Techniques Of The Embedded Real-time Java Virtual Machine

As the technology of Java is applied in the real-time system, the real-time Java technology emerges. At the same time, higher requirements will be made on Java virtual machine, the platform of Java application, for the using of the real-time Java. Moreover, it also accelerates the research and development of the embedded real-time Java virtual machine.ARTs-OS is an embedded real-time operating system developed by Huaxiang Software Research and Development Centre. ARTs-JVM is a real-time middleware based on the system, used to support the real-time Java applications in embedded real-time environments.ARTs-JVM is composed of the class-loader, verifier, intializer, scheduler, garbage collector and the run-time environments. And the interpreter is the heart of the ARTs-JVM. Designing the runtime environment is the basis of the designing and realizing the ARTs-JVM, and it is also the basic guarantee of realizing the features of real-time for ARTs-JVM.As the basis of the Java's characteristic and being independent of the platform, the class file includes a lot of information needed in run-time. Java virtual machine executes on stack. Whenever a thread is created, it will allocate a stack for the new thread. When invocating a method, a structure for stack frame is saved in the stack; the structure of Method is the basement of the execution of Java virtual machine, and the running process is also the process of invoking method.There are many critical technologies in designing and realizing the embedded real-time Java virtual machine, including real-time thread scheduling and embedded real-time garbage collection and so on.In the real-time scheduling, ARTs-JVM adopts the priority-driven preemptive scheduling module, ensuing the consistence with the ARTs-OS, in order to realizing the support for the thread in languages for Java. And it also adopts the mechanism of priority-inheritance to avoid the priority inversion produced by the Lock. In the embedded real-time garbage collection, ARTs-JVM reaches the blueprint in accordance with the features of the embedded real-time GC, exact, increasing and no fragment.