Implementing SOS with active objects: A case study of a multicore memory system

This paper describes the development of a parallel simulator of a multicore memory system from a model formalized as a structural operational semantics (SOS). Our implementation uses the Abstract Behavioral Specification (ABS) language, an executable, active object modelling language with a formal semantics, targeting distributed systems. We develop general design patterns in ABS for implementing SOS, and describe their application to the SOS model of multicore memory systems. We show how these patterns allow a formal correctness proof that the implementation simulates the formal operational model and discuss further parallelization and fairness of the simulator

From SOS to Asynchronously Communicating Actors

Structural Operational Semantics (SOS) provides a general format to describe a model as a transition system with very powerful synchronization mechanisms. Actor systems are distributed, asynchronously communicating units of computation with encapsulated state, with much weaker means of synchronizing between actors. In this paper, we discuss an implementation of a SOS model using actors in the object-oriented actor language ABS and how to argue that global properties about the model are inherited from the SOS level to the actor implementation. The work stems from a case study modelling the memory system of a cache-coherent multicore architecture

Inseguendo fagiani selvatici: Partial order reduction for guarded command languages

This paper presents a method for testing whether objects in actor languages and active object languages exhibit locally deterministic behavior. We investigate such a method for a class of guarded command programs, abstracting from object-oriented features like method calls but focusing on cooperative scheduling of dynamically spawned processes executing in parallel. The proposed method can answer questions such as whether all permutations of an execution trace are equivalent, by generating candidate traces for testing which may lead to different final states. To prune the set of candidate traces, we employ partial order reduction. To further reduce the set, we introduce an analysis technique to decide whether a generated trace is schedulable. Schedulability cannot be decided for guarded commands using standard dependence and interference relations because guard enabledness is non-monotonic. To solve this problem, we use concolic execution to produce linearized symbolic traces of the executed program, which allows a weakest precondition computation to decide on the satisfiability of guards