Commit and free

We have already enountered functions MPI_Type_commit and MPI_Type_free so here I just give their definitions for completeness:

• C:

  MPI_Type_commit(MPI_Datatype *datatype)
  

  Fortran:

  mpi_type_commit(datatype, ierror)
     integer datatype, ierror
  

  In principle this function is supposed to generate a formal description of the communication buffer, which is then going to be used by consequent communication operations on this or other similar buffers. The system, on receiving this call, may compile the datatype and generate an internal representation of it. The most convenient transfer mechanism, for this datatype, may be selected too.
• C:

  MPI_Type_free(MPI_Datatype *datatype)
  

  Fortran:

  mpi_type_free(datatype, ierror)
     integer datatype, ierror
  

  The datatype is set to MPI_DATATYPE_NULL. All pending communications that use this datatype complete normally. Datatypes derived from the freed datatype are not affected.