MPI_Comm_idup(3) Open MPI MPI_Comm_idup(3)
NAME
MPI_Comm_idup - Start the nonblocking duplication of an existing com-
municator with all its cached information.
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 commu-
nicator comm with associated key values. For each key value, the re-
spective copy callback function determines the attribute value associ-
ated with this key in the new communicator; one particular action that
a copy callback may take is to delete the attribute from the new commu-
nicator. 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"). 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 dupli-
cate 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 in-
volving 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 at-
tribute 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 value
of the function and Fortran routines in the last argument.
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.
SEE ALSO
MPI_Comm_dup MPI_Comm_dup_with_info
4.1.2 Nov 24, 2021 MPI_Comm_idup(3)
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