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MPI_Comm_free(3) MPI MPI_Comm_free(3)

NAME

MPI_Comm_free - Marks the communicator object for deallocation

SYNOPSIS



int MPI_Comm_free(MPI_Comm *comm)










INPUT/OUTPUT PARAMETERS



  

  
- 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.





  

  
- No error; MPI routine completed successfully.

  

  
- Invalid communicator. A common error is to use a null communicator in a
      call (not even allowed in MPI_Comm_rank ).

  

  
- Other error; use MPI_Error_string to get more information about
      this error code.
    

  









  

    2/9/2024