Making Asynchronous Parallelism Safe for the World


Guy L. Steele, Thinking Machines Corporation, 1990

    We need a programming model that combines the advantages of the synchronous and asynchronous parallel styles. Synchronous programs are determinate (thus easier to reason about) and avoid synchronization overheads. Asynchronous programs are more flexible and handle conditions more efficiently.

    Here we propose a programming model with the benefits of both styles. We allow asynchronous threads of control but restrict shared-memory accesses and other side effects so as to prevent the behavior of the program from depending on any accidents of execution order that can arise from the indeterminacy of the asynchronous process model.

This paper and the ones below may be of special interest in light of the current discussion of modern parallel computer architectures.