SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Add_error_class(int *errorclass)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_ADD_ERROR_CLASS(ERRORCLASS, IERROR)
               INTEGER ERRORCLASS, IERROR

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_Add_error_class(errorclass, ierror)
               INTEGER, INTENT(OUT) :: errorclass
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

OUTPUT PARAMETERS

       • errorclass: New error class (integer).

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

DESCRIPTION

       The function MPI_Add_error_class creates a new, local error class.

NOTES

       Because  this  function  is local, the same value of errorclass may not be returned on all processes that
       make this call, even if they call the function concurrently. Thus, same error on different processes  may
       not  cause  the  same  value  of  errorclass  to  be  returned.  To  reduce  the potential for confusion,
       MPI_Add_error_string may be used on multiple processes to associate the same error string with the  newly
       created   errorclass.   Even   though   errorclass   may   not  be  consistent  across  processes,  using
       MPI_Add_error_string will ensure the error string associated with it will be the same everywhere.

       No function is provided to free error classes, as it is not expected that an application will create them
       in significant numbers.

       The value returned is always greater than or equal to MPI_ERR_LASTCODE.

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.

       SEE ALSO:

          • MPI_Add_error_code

          • MPI_Add_error_string

          • MPI_Error_class

          • MPI_Error_string

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                            MPI_ADD_ERROR_CLASS(3)