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.TH "MPI_COMM_GET_NAME" "3" "Apr 11, 2024" "" "Open MPI"
.sp
\fI\%MPI_Comm_get_name\fP — Returns the name that was most recently
associated with a communicator.
.SH SYNTAX
.SS C Syntax
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.INDENT 3.5
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.EX
#include <mpi.h>

int MPI_Comm_get_name(MPI_Comm comm, char *comm_name, int *resultlen)
.EE
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.SS Fortran Syntax
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.INDENT 3.5
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.EX
USE MPI
! or the older form: INCLUDE \(aqmpif.h\(aq
MPI_COMM_GET_NAME(COMM, COMM_NAME, RESULTLEN, IERROR)
     INTEGER COMM, RESULTLEN, IERROR
     CHARACTER*(*) COMM_NAME
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.SS Fortran 2008 Syntax
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.EX
USE mpi_f08
MPI_Comm_get_name(comm, comm_name, resultlen, ierror)
     TYPE(MPI_Comm), INTENT(IN) :: comm
     CHARACTER(LEN=MPI_MAX_OBJECT_NAME), INTENT(OUT) :: comm_name
     INTEGER, INTENT(OUT) :: resultlen
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror
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.SH INPUT PARAMETER
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.IP \(bu 2
\fBcomm\fP: Communicator the name of which is to be returned (handle).
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.SH OUTPUT PARAMETER
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.IP \(bu 2
\fBcomm_name\fP: Name previously stored on the communicator, or an empty string if no such name exists (string).
.IP \(bu 2
\fBresultlen\fP: Length of returned name (integer).
.IP \(bu 2
\fBierror\fP: Fortran only: Error status (integer).
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.SH DESCRIPTION
.sp
\fI\%MPI_Comm_get_name\fP returns the last name that was previously associated
with the given communicator. The name may be set and retrieved from any
language. The same name will be returned independent of the language
used. \fIcomm_name\fP should be allocated so that it can hold a resulting
string of length MPI_MAX_OBJECT_NAME characters. \fI\%MPI_Comm_get_name\fP
returns a copy of the set name in \fIcomm_name\fP\&.
.sp
If the user has not associated a name with a communicator, or an error
occurs, \fI\%MPI_Comm_get_name\fP will return an empty string (all spaces in
Fortran, “” in C). The three predefined communicators will have
predefined names associated with them. Thus, the names of
MPI_COMM_WORLD, MPI_COMM_SELF, and MPI_COMM_PARENT will have the default
of MPI_COMM_WORLD, MPI_COMM_SELF, and MPI_COMM_PARENT. The fact that the
system may have chosen to give a default name to a communicator does not
prevent the user from setting a name on the same communicator; doing
this removes the old name and assigns the new one.
.SH NOTES
.sp
It is safe simply to print the string returned by \fI\%MPI_Comm_get_name\fP, as
it is always a valid string even if there was no name.
.sp
Note that associating a name with a communicator has no effect on the
semantics of an MPI program, and will (necessarily) increase the store
requirement of the program, since the names must be saved. Therefore,
there is no requirement that users use these functions to associate
names with communicators. However debugging and profiling MPI
applications may be made easier if names are associated with
communicators, since the debugger or profiler should then be able to
present information in a less cryptic manner.
.SH ERRORS
.sp
Almost all MPI routines return an error value; C routines as the return result
of the function and Fortran routines in the last argument.
.sp
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
\fI\%MPI_Init\fP/\fI\%MPI_Init_thread\fP, after \fI\%MPI_Finalize\fP, or when using the Sessions
Model exclusively) the error raises the initial error handler. The initial
error handler can be changed by calling \fI\%MPI_Comm_set_errhandler\fP on
MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI
argument to mpiexec or info key to \fI\%MPI_Comm_spawn\fP/\fI\%MPI_Comm_spawn_multiple\fP\&.
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.
.sp
Open MPI includes three predefined error handlers that can be used:
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\fBMPI_ERRORS_ARE_FATAL\fP
Causes the program to abort all connected MPI processes.
.IP \(bu 2
\fBMPI_ERRORS_ABORT\fP
An error handler that can be invoked on a communicator,
window, file, or session. When called on a communicator, it
acts as if \fI\%MPI_Abort\fP was called on that communicator. If
called on a window or file, acts as if \fI\%MPI_Abort\fP 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.
.IP \(bu 2
\fBMPI_ERRORS_RETURN\fP
Returns an error code to the application.
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MPI applications can also implement their own error handlers by calling:
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.IP \(bu 2
\fI\%MPI_Comm_create_errhandler\fP then \fI\%MPI_Comm_set_errhandler\fP
.IP \(bu 2
\fI\%MPI_File_create_errhandler\fP then \fI\%MPI_File_set_errhandler\fP
.IP \(bu 2
\fI\%MPI_Session_create_errhandler\fP then \fI\%MPI_Session_set_errhandler\fP or at \fI\%MPI_Session_init\fP
.IP \(bu 2
\fI\%MPI_Win_create_errhandler\fP then \fI\%MPI_Win_set_errhandler\fP
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.sp
Note that MPI does not guarantee that an MPI program can continue past
an error.
.sp
See the \fI\%MPI man page\fP for a full list of \fI\%MPI error codes\fP\&.
.sp
See the Error Handling section of the MPI\-3.1 standard for
more information.
.SH COPYRIGHT
2003-2024, The Open MPI Community
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