In the spirit of the previous question, learn about the SHMEM library package, originally developed by Robert Numrich of Cray, Inc., and now standardized as OpenSHMEM (openshmem.org). SHMEM is widely...

In the spirit of the previous question, learn about the SHMEM library package, originally developed by Robert Numrich of Cray, Inc., and now standardized as OpenSHMEM (openshmem.org). SHMEM is widely used for parallel programming on both large-scale multiprocessors and clusters. It has been characterized as a cross between shared memory and message passing. Is this a fair characterization? Under what circumstances might a shmem program be expected to outperform solutions in MPI or OpenMP?