plucky (3) MPI_Comm_idup.openmpi.3.gz

SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Comm_idup(MPI_Comm comm, MPI_Comm *newcomm, MPI_Request *request)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_COMM_IDUP(COMM, NEWCOMM, REQUEST, IERROR)
               INTEGER COMM, NEWCOMM, REQUEST, IERROR

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_Comm_idup(comm, newcomm, request, ierror)
               TYPE(MPI_Comm), INTENT(IN) :: comm
               TYPE(MPI_Comm), INTENT(OUT) :: newcomm
               TYPE(MPI_Request), INTENT(OUT) :: request
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER

       • comm: Communicator (handle).

OUTPUT PARAMETERS

       • newcomm: Copy of comm (handle).

       • request: Communication request (handle).

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

DESCRIPTION

       MPI_Comm_idup  starts  the  nonblocking  duplication of an existing communicator comm with associated key
       values. For each key value,  the  respective  copy  callback  function  determines  the  attribute  value
       associated  with this key in the new communicator; one particular action that a copy callback may take is
       to delete the attribute from the new communicator. Returns in newcomm a new communicator  with  the  same
       group,  any  copied  cached  information,  but  a  new context (see the “Functionality” subsection of the
       “Caching” section in the “Groups, Contexts,  and  Communicators”  chapter  in  the  MPI  Standard).   The
       communicator returned in newcomm will not be available until the request is complete.

       The  completion  of  a  communicator  duplication  request  can be determined by calling any of MPI_Wait,
       MPI_Waitany, MPI_Test, or MPI_Testany with the request returned by this function.

NOTES

       This operation is used to provide a parallel library call with a duplicate communication space  that  has
       the same properties as the original communicator. This includes any attributes (see below) and topologies
       (see the “Process Topologies” chapter in the MPI Standard).  This call is valid even if there are pending
       point-to-point  communications  involving  the  communicator  comm.  A  typical  call  might  involve  an
       MPI_Comm_idup at the beginning of the parallel call, and an MPI_Comm_free of that duplicated communicator
       at the end of the call.  Other models of communicator management are also possible.

       This call applies to both intra- and intercommunicators.

       Note that it is not defined by the MPI standard what happens if the attribute copy callback invokes other
       MPI functions. In Open MPI, it is not valid for attribute copy callbacks (or any of  their  children)  to
       add or delete attributes on the same object on which the attribute copy callback is being invoked.

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_dup

          • MPI_Comm_dup_with_info

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                                  MPI_COMM_IDUP(3)