Illegal references in a real-time Java']Java concurrent environment

We consider the concurrent execution of several applications within a single JVM. In order to have a different GC per application, we introduce and define application-specific memory, building upon the Real-Time Specification for Java (RTSJ) from the Real-Time Java Expert Group. The RTSJ memory model imposes strict assignment rules to or from memory areas preventing the creation of dangling pointers. An implementation solution to ensure the pointer safety of Java consists to check the imposed rules before executing each assignment statement by using write barriers.