Jean-Marie Dautelle

The Java platform is usually perceived as inadequate for real-time applications because of its lack of determinism, that is, its unpredictable execution time. For example, garbage collection (GC), which removes no-longer-needed Java objects and reduces memory overhead, may automatically and transparently freeze the system from time to time. Such behavior is obviously unacceptable in the real-time world. (A commonly recognized goal of real-time computing is to meet an application's time constraints.) To address this issue, new Java Virtual Machines (JVM) are being developed (e.g., JVM with concurrent GC). In addition, a new Real-Time Specification for Java (RTSJ, JSR-001) has been finalized. Unfortunately, these solutions achieve predictability to the detriment of performance. For example, concurrent GC is less efficient than "stop the world GC" (which requires tota... (more)