A Comparison of the Mutual Exclusion Features in Ada and the Real-Time Specification for Java TM

A concurrent program generally comprises a collection of threads1 that interact cooperatively, either directly or through shared data objects. In the latter case the sharing needs to be implemented by some mechanism that ensures mutually exclusive access, or possibly “concurrent read / exclusive write”. Ada and the Real-Time Specification for Java have taken different approaches to mutual exclusion. This paper analyzes and compares them with respect to programming style (clarity, encapsulation, avoidance of errors such as deadlock), priority inversion management, expressibility/generality, and efficiency. It also looks at interactions with exceptions and asynchronous transfer of control.