Parallel programming must be deterministic by default

In today's widely used parallel programming models, subtle programming errors can lead to unintended nondeterministic behavior and hard to catch bugs. In contrast, we argue for a parallel programming model that is deterministic by default: deterministic behavior is guaranteed unless the programmer explicitly uses nondeterministic constructs. This goal is particularly challenging for modern object-oriented languages with expressive use of reference aliasing and updates to shared mutable state. We propose a broad research agenda in support of this goal, and we describe some of our own work to further that agenda.