plucky (3) MPI_Comm_get_name.openmpi.3.gz

SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Comm_get_name(MPI_Comm comm, char *comm_name, int *resultlen)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_COMM_GET_NAME(COMM, COMM_NAME, RESULTLEN, IERROR)
               INTEGER COMM, RESULTLEN, IERROR
               CHARACTER*(*) COMM_NAME

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_Comm_get_name(comm, comm_name, resultlen, ierror)
               TYPE(MPI_Comm), INTENT(IN) :: comm
               CHARACTER(LEN=MPI_MAX_OBJECT_NAME), INTENT(OUT) :: comm_name
               INTEGER, INTENT(OUT) :: resultlen
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER

       • comm: Communicator the name of which is to be returned (handle).

OUTPUT PARAMETER

       • comm_name:  Name  previously  stored  on  the  communicator,  or an empty string if no such name exists
         (string).

       • resultlen: Length of returned name (integer).

       • ierror: Fortran only: Error status (integer).

DESCRIPTION

       MPI_Comm_get_name returns the last name that was previously associated with the given  communicator.  The
       name  may  be  set  and  retrieved  from  any language. The same name will be returned independent of the
       language used. comm_name should  be  allocated  so  that  it  can  hold  a  resulting  string  of  length
       MPI_MAX_OBJECT_NAME characters. MPI_Comm_get_name returns a copy of the set name in comm_name.

       If  the  user  has  not associated a name with a communicator, or an error occurs, MPI_Comm_get_name will
       return an empty string (all spaces in Fortran, “” in C). The three  predefined  communicators  will  have
       predefined   names   associated  with  them.  Thus,  the  names  of  MPI_COMM_WORLD,  MPI_COMM_SELF,  and
       MPI_COMM_PARENT will have the default of MPI_COMM_WORLD, MPI_COMM_SELF,  and  MPI_COMM_PARENT.  The  fact
       that  the  system may have chosen to give a default name to a communicator does not prevent the user from
       setting a name on the same communicator; doing this removes the old name and assigns the new one.

NOTES

       It is safe simply to print the string returned by MPI_Comm_get_name, as it is always a valid string  even
       if there was no name.

       Note  that  associating  a name with a communicator has no effect on the semantics of an MPI program, and
       will (necessarily) increase the store requirement  of  the  program,  since  the  names  must  be  saved.
       Therefore,  there is no requirement that users use these functions to associate names with communicators.
       However debugging and profiling MPI applications  may  be  made  easier  if  names  are  associated  with
       communicators,  since  the  debugger  or  profiler  should  then be able to present information in a less
       cryptic manner.

ERRORS

       Almost all MPI routines return an error value; C routines as  the  return  result  of  the  function  and
       Fortran routines in the last argument.

       Before  the  error  value  is  returned,  the current MPI error handler associated with the communication
       object (e.g., communicator, window, file) is called.  If no communication object is associated  with  the
       MPI  call,  then  the call is considered attached to MPI_COMM_SELF and will call the associated MPI error
       handler.  When  MPI_COMM_SELF  is  not  initialized   (i.e.,   before   MPI_Init/MPI_Init_thread,   after
       MPI_Finalize,  or  when using the Sessions Model exclusively) the error raises the initial error handler.
       The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF  when  using
       the  World  model,  or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/‐
       MPI_Comm_spawn_multiple.  If no other appropriate error handler has been set, then the  MPI_ERRORS_RETURN
       error  handler  is  called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
         called  on  a  communicator,  it  acts  as if MPI_Abort was called on that communicator. If called on a
         window or file, acts as if MPI_Abort was called on a communicator containing the group of processes  in
         the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

       See the Error Handling section of the MPI-3.1 standard for more information.

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                              MPI_COMM_GET_NAME(3)