NAME

       MPI_Comm_free -  Marks the communicator object for deallocation

SYNOPSIS

       int MPI_Comm_free(MPI_Comm *comm)

INPUT/OUTPUT PARAMETERS

       comm   - communicator to be destroyed (handle)

NOTES

       This  routine  frees a communicator.  Because the communicator may still be in use by other MPI routines,
       the actual communicator storage will not be freed until all references to this communicator are  removed.
       For  most  users,  the effect of this routine is the same as if it was in fact freed at this time of this
       call.

NULL HANDLES

       The MPI 1.1 specification, in the section on opaque objects, explicitly

DISALLOWS FREEING A NULL COMMUNICATOR. THE TEXT FROM THE STANDARD IS

       A null handle argument is an erroneous IN argument in MPI calls, unless an
       exception is explicitly stated in the text that defines the function. Such
       exception is allowed for handles to request objects in Wait and Test calls
       (sections Communication Completion and Multiple Completions). Otherwise, a
       null handle can only be passed to a function that allocates a new object and
       returns a reference to it in the handle.

THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely used by multiple threads without
       the  need  for  any  user-provided thread locks.  However, the routine is not interrupt safe.  Typically,
       this is due to the use of memory allocation routines such as malloc or other non-MPICH  runtime  routines
       that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have an additional argument ierr at the
       end of the argument list.  ierr is an integer and has the same meaning as the return value of the routine
       in C.  In Fortran, MPI routines are subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI routines (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as the value of the
       function and Fortran routines in the last argument.  Before the value is returned, the current MPI  error
       handler  is called.  By default, this error handler aborts the MPI job.  The error handler may be changed
       with   MPI_Comm_set_errhandler   (for   communicators),   MPI_File_set_errhandler   (for   files),    and
       MPI_Win_set_errhandler  (for  RMA windows).  The MPI-1 routine MPI_Errhandler_set may be used but its use
       is deprecated.  The predefined error handler MPI_ERRORS_RETURN may be used to cause error  values  to  be
       returned.   Note that MPI does not guarantee that an MPI program can continue past an error; however, MPI
       implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_COMM
              - Invalid communicator.  A common error is to use a null communicator in a call (not even  allowed
              in MPI_Comm_rank ).
       MPI_ERR_OTHER
              - Other error; use MPI_Error_string to get more information about this error code.

                                                    2/9/2024                                    MPI_Comm_free(3)