Portable, MPI-Interoperable Coarray Fortran

The past decade has seen the advent of a number of parallel programming models such as Coarray Fortran (CAF), Uni-fied Parallel C, X10, and Chapel. Despite the productivity gains promised by these models, most parallel scientific ap-plications still rely on MPI as their data movement model. One reason for this trend is that it is hard for users to incre-mentally adopt these new programming models in existing MPI applications. Because each model use its own runtime system, they duplicate resources and are potentially error-prone. Such independent runtime systems were deemed nec-essary because MPI was considered insufficient in the past to play this role for these languages. The recently released MPI-3, however, adds several new capabilities that now provide all of the functionality needed to act as a runtime, including a much more comprehensive one-sided communication framework. In this paper, we in-vestigate how MPI-3 can form a runtime system for one ex-ample programming model, CAF, with a broader goal of en-abling a single application to use both MPI and CAF with the highest level of interoperability