MPI_Comm_dup(3)                    Open MPI                    MPI_Comm_dup(3)



NAME
       MPI_Comm_dup  -  Duplicates an existing communicator with all its
       cached information.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Comm_dup(MPI_Comm comm, MPI_Comm *newcomm)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_COMM_DUP(COMM, NEWCOMM, IERROR)
            INTEGER   COMM, NEWCOMM, IERROR


C++ Syntax
       #include <mpi.h>
       Intracomm Intracomm::Dup() const

       Intercomm Intercomm::Dup() const


INPUT PARAMETER
       comm      Communicator (handle).


OUTPUT PARAMETERS
       newcomm   Copy of comm (handle).

       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPI_Comm_dup duplicates the 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 Section 5.7.1 of the MPI-1 Standard,
       "Functionality").


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 Chapter 6, "Process Topologies," in the MPI-1
       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_dup 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.


ERRORS
       Almost all MPI routines return an error value; C routines as the value
       of the function and Fortran routines in the last argument. C++
       functions do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before the error value is returned, the current MPI error handler is
       called. By default, this error handler aborts the MPI job, except for
       I/O function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
       may be used to cause error values to be returned. Note that MPI does
       not guarantee that an MPI program can continue past an error.





1.4.1                            Jan 14, 2010                  MPI_Comm_dup(3)
