Toward a Formal Semantic Framework for Deterministic Parallel Programming ∗

Deterministic parallelism has become an increasingly attractive concept: a deterministic parallel program may be easier to construct, debug, understand, and maintain. However, there exist many different definitions of “determinism” for parallel programming. Many existing definitions have not yet been fully formalized, and the relationships among these definitions are still unclear. We argue that formalism is needed, and that history-based operational semantics— as used, for example, to define the Java and C++ memory models—provides a useful lens through which to view the notion of determinism. As a first step, we suggest several history-based definitions of determinism. We discuss some of their comparative advantages, note containment relationships among them, and identify programming idioms that support them. We also propose directions for future work. 1

Message race detection for web services by an smt-based analysis

Abstract. The success of the cloud computing initiative is heavily dependent on realizing trustworthy Web Services. The trustworthiness of a Web Service is judged by four factors: security, privacy, reliability and business integrity. Web Services use message-passing for communication which opens the door for messages races. Messages race with each other when their order of arrival at a destination is not guaranteed and is affected non-deterministically by factors such as network latencies and scheduling variations. Message races are dangerous to Web Services because they can be unforeseen consequences of bugs, causing messages to arrive in an unexpected ordering. In this paper we present a novel approach for improving the reliability of Web Services by detecting message races using SMT-based analysis. We model a BPEL process as a Web Service Modeling Graph (WSMG). A WSMG model is then encoded into a set of SMT constraints. The satisfiability of these constraints means that message races will occur during the actual execution of the Web Service. Hence, we reduce the message race detection problem to constraint solving problem based on satisfiability modulo theories (SMT)