A Comparison of Co-Array Fortran and OpenMP Fortran for SPMD Programming

Co-Array Fortran, formally called F−−, is a small set of extensions to Fortran 90/95 for Single-Program-Multiple-Data (SPMD) parallel processing. OpenMP Fortran is a set of compiler directives that provide a high level interface to threads in Fortran, with both thread-local and thread-shared memory. OpenMP is primarily designed for loop-level directive-based parallelization, but it can also be used for SPMD programs by spawning multiple threads as soon as the program starts and having each thread then execute the same code independently for the duration of the run. The similarities and differences between these two SPMD programming models are described.