SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Comm_connect(const char *port_name, MPI_Info info, int root,
              MPI_Comm comm, MPI_Comm *newcomm)

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

          MPI_COMM_CONNECT(PORT_NAME, INFO, ROOT, COMM, NEWCOMM, IERROR)
              CHARACTER*(*)   PORT_NAME
              INTEGER     INFO, ROOT, COMM, NEWCOMM, IERROR

   Fortran 2008 Syntax
          USE mpi_f08

          MPI_Comm_connect(port_name, info, root, comm, newcomm, ierror)
              CHARACTER(LEN=*), INTENT(IN) :: port_name
              TYPE(MPI_Info), INTENT(IN) :: info
              INTEGER, INTENT(IN) :: root
              TYPE(MPI_Comm), INTENT(IN) :: comm
              TYPE(MPI_Comm), INTENT(OUT) :: newcomm
              INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

       • port_name : Port name (string, used only on root).

       •

         info (Options given by root for the connect (handle, used only on)
                root). No options currently supported.

       • root : Rank in comm of root node (integer).

       • comm : Intracommunicator over which call is collective (handle).

OUTPUT PARAMETERS

       • newcomm : Intercommunicator with client as remote group (handle)

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

DESCRIPTION

       MPI_Comm_connect  establishes  communication  with a server specified by port_name. It is collective over
       the calling communicator and returns an intercommunicator in which the remote group  participated  in  an
       MPI_Comm_accept.  The  MPI_Comm_connect  call must only be called after the MPI_Comm_accept call has been
       made by the MPI job acting as the server.  If the named  port  does  not  exist  (or  has  been  closed),
       MPI_Comm_connect  raises  an  error  of  class  MPI_ERR_PORT.  MPI  provides  no guarantee of fairness in
       servicing connection attempts. That is, connection attempts are not necessarily satisfied in the order in
       which they were initiated, and competition from  other  connection  attempts  may  prevent  a  particular
       connection attempt from being satisfied. The port_name parameter is the address of the server. It must be
       the same as the name returned by MPI_Open_port on the server.

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_accept

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                               MPI_COMM_CONNECT(3)