SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Comm_disconnect(MPI_Comm *comm)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'

          MPI_COMM_DISCONNECT(COMM, IERROR)
              INTEGER COMM, IERROR

   Fortran 2008 Syntax
          USE mpi_f08

          MPI_Comm_disconnect(comm, ierror)
              TYPE(MPI_Comm), INTENT(INOUT) :: comm
              INTEGER, OPTIONAL, INTENT(OUT) :: ierror

   INPUT/OUTPUT PARAMETER
       • comm : Communicator (handle).

OUTPUT PARAMETER

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

DESCRIPTION

       MPI_Comm_disconnect  waits  for all pending communication on comm to complete internally, deallocates the
       communicator object, and sets the handle to MPI_COMM_NULL. It is a collective operation. It  may  not  be
       called  with the communicator MPI_COMM_WORLD or MPI_COMM_SELF.  MPI_Comm_disconnect may be called only if
       all communication is complete and matched, so that buffered data can be  delivered  to  its  destination.
       This  requirement  is  the  same  as  for  MPI_Finalize.  MPI_Comm_disconnect  has  the  same  action  as
       MPI_Comm_free, except that it waits for pending  communication  to  finish  internally  and  enables  the
       guarantee about the behavior of disconnected processes.

NOTES

       To disconnect two processes you may need to call MPI_Comm_disconnect, MPI_Win_free, and MPI_File_close to
       remove  all  communication  paths  between the two processes. Note that it may be necessary to disconnect
       several communicators (or to  free  several  windows  or  files)  before  two  processes  are  completely
       independent.

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_Comm_connect

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                            MPI_COMM_DISCONNECT(3)