Deadlock analysis of synchronous message-passing programs

Reachability analysis of a concurrent program involves the derivation of states of the program and the detection of deadlocks and other types of faults. To perform reachability analysis of a concurrent program P, the number of instances of each process type in P needs to be determined. How to select such numbers for P is a difficult issue. If these numbers are large, reachability analysis of P needs huge memory and very long CPU time. If these numbers are small, we have little confidence on whether P is deadlock-free for larger numbers of instances of process types in P. A deadlock cutoff number C for a process type T in P means that if under certain conditions P with C instances of T has no deadlocks, then P has no dead locks for any number of instances of T. We describe methods for finding deadlock cutoff numbers for three types of synchronous message-passing programs. Our methods are based on the theory of Milner´s CCS. By applying these methods, the effort for detecting deadlocks in many synchronous message-passing programs can be significantly reduced. Empirical results of applying our methods to solutions to the dining philosophers and readers and writers problems are presented