Allowing Cycle References by Introducing Controlled Violations of the Assignment Rules in Real-Time Java

The real-time specification for Java (RTSJ) extends the Java memory model through immortal and scoped memory regions to reduce the timing-indeterminism caused by garbage collection. Since scoped regions can be nested, RTSJ imposes strict assignment rules to avoid dangling pointers. These rules stabilise that an object shall not reference any object whose lifetime could be shorter than they own. Then references among two objects within different scoped regions are allowed only in one direction (i.e., from objects within region r1 to region r2, but never from r2 to r1). In order to support RTSJ component-based applications, we require controlled violations of the assignment rules to have bidirectional references among objects within two different scopes.