Decidability of Liveness on the TSO Memory Model

Abstract

An important property of concurrent objects is whether they support progress -a special case of liveness -guarantees, which ensure the termination of individual method calls under system fairness assumptions. Liveness properties have been proposed for concurrent objects. Typical liveness properties include lock-freedom, wait-freedom, deadlock-freedom, starvation-freedom and obstructionfreedom. It is known that the five liveness properties above are decidable on the Sequential Consistency (SC) memory model for a bounded number of processes. However, the problem of decidability of liveness for finite state concurrent programs running on relaxed memory models remains open. In this paper we address this problem for the Total Store Order (TSO) memory model, as found in the x86 architecture. We prove that lock-freedom, wait-freedom, deadlock-freedom and starvation-freedom are undecidable on TSO for a bounded number of processes, while obstruction-freedom is decidable.