Blocking time monitoring in the Real-Time Specification for Java

Blocking for resource accesses can have a crucial impact on a real-time system’s ability to meet its deadlines. In priority-based systems, uncontrolled blocking can lead to potentially unbound priority inversion. To counteract this, basic priority inheritance and priority ceiling protocols have been defined. However, in large systems, it is still difficult to determine the maximum amount of blocking that a thread can suffer when using these protocols. The Real-Time Specification for Java provides a framework for execution and on-line feasibility analysis of priority-based systems. In this paper, we investigate possible extensions to this framework to support the measurement and monitoring of blocking times. We implement and evaluate the proposed mechanism with the context of the open source JRate implementation of the RTSJ running on top of the MaRTE OS.