MPI_Comm_dup(3) MPI MPI_Comm_dup(3)NAMEMPI_Comm_dup - Duplicates an existing communicator with all its cached
information
SYNOPSIS
int MPI_Comm_dup(MPI_Comm comm, MPI_Comm *newcomm)
INPUT PARAMETERS
comm - Communicator to be duplicated (handle)
OUTPUT PARAMETERS
newcomm
- A new communicator over the same group as comm but with a new
context. See notes. (handle)
NOTES
This routine is used to create a new communicator that has a new commu‐
nication context but contains the same group of processes as the input
communicator. Since all MPI communication is performed within a commu‐
nicator (specifies as the group of processes plus the context), this
routine provides an effective way to create a private communicator for
use by a software module or library. In particular, no library routine
should use MPI_COMM_WORLD as the communicator; instead, a duplicate of
a user-specified communicator should always be used. For more informa‐
tion, see Using MPI, 2nd edition.
Because this routine essentially produces a copy of a communicator, it
also copies any attributes that have been defined on the input communi‐
cator, using the attribute copy function specified by the copy_function
argument to MPI_Keyval_create . This is particularly useful for (a)
attributes that describe some property of the group associated with the
communicator, such as its interconnection topology and (b) communica‐
tors that are given back to the user; the attibutes in this case can
track subsequent MPI_Comm_dup operations on this communicator.
THREAD AND INTERRUPT SAFETY
This routine is thread-safe. This means that this routine may be
safely used by multiple threads without the need for any user-provided
thread locks. However, the routine is not interrupt safe. Typically,
this is due to the use of memory allocation routines such as malloc or
other non-MPICH runtime routines that are themselves not interrupt-
safe.
NOTES FOR FORTRAN
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
an additional argument ierr at the end of the argument list. ierr is
an integer and has the same meaning as the return value of the routine
in C. In Fortran, MPI routines are subroutines, and are invoked with
the call statement.
All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
Fortran.
ERRORS
All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
value; C routines as the value of the function and Fortran routines in
the last argument. Before the value is returned, the current MPI error
handler is called. By default, this error handler aborts the MPI job.
The error handler may be changed with MPI_Comm_set_errhandler (for com‐
municators), MPI_File_set_errhandler (for files), and
MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine
MPI_Errhandler_set may be used but its use is deprecated. The prede‐
fined error handler MPI_ERRORS_RETURN may be used to cause error values
to be returned. Note that MPI does not guarentee that an MPI program
can continue past an error; however, MPI implementations will attempt
to continue whenever possible.
MPI_SUCCESS
- No error; MPI routine completed successfully.
MPI_ERR_COMM
- Invalid communicator. A common error is to use a null commu‐
nicator in a call (not even allowed in MPI_Comm_rank ).
SEE ALSO
MPI_Comm_free, MPI_Keyval_create, MPI_Attr_put, MPI_Attr_delete,
MPI_Comm_create_keyval, MPI_Comm_set_attr, MPI_Comm_delete_attr
LOCATION
src/mpi/comm/comm_dup.c
8/22/2013 MPI_Comm_dup(3)
