问题
Can anyone help me get my head around the MPI Groups, Inter and Intra communicators. I have already gone through the MPI documentation(http://www.mpi-forum.org/docs/mpi-2.2/mpi22-report.pdf ) and I couldnt make good sense of these concepts. I would especially appreciate any code in the area of Inter communicators and communicator partitioning into groups within one communicator e.g. (MPI_COMM_WORLD) this is because I think I can also learn by experimenting on live code .
回答1:
Can you expand upon what specifically doesn't make sense to you?
Generally speaking, however, I can say this: An MPI group is a set of processes. An MPI communicator is a way of talking between processes. If the communication is within a single group, then you are using an intracommunicator. If the communication is between two disjoing groups, then you're using an intercommunicator.
While you generally think of a communicator as spanning processes, each communicator is actually unique to a process. A communicator can be thought of as a handle to an object (group attribute) that describes a group of processes.
来源：https://stackoverflow.com/questions/32468876/can-anyone-help-me-understand-how-mpi-communicator-groups-partitioning-works