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.TH "MPI_COMM_SET_INFO" "3" "May 30, 2025" "" "Open MPI"
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.sp
\fI\%MPI_Comm_set_info\fP — Set communicator info hints
.SH SYNTAX
.SS C Syntax
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
#include <mpi.h>

int MPI_Comm_set_info(MPI_Comm comm, MPI_Info info)
.ft P
.fi
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.SS Fortran Syntax
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.INDENT 3.5
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.nf
.ft C
USE MPI
! or the older form: INCLUDE \(aqmpif.h\(aq
MPI_COMM_SET_INFO(COMM, INFO, IERROR)
     INTEGER COMM, INFO, IERROR
.ft P
.fi
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.SS Fortran 2008 Syntax
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.INDENT 3.5
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.nf
.ft C
USE mpi_f08
MPI_Comm_set_info(comm, info, ierror)
     TYPE(MPI_Comm), INTENT(IN) :: comm
     TYPE(MPI_Info), INTENT(IN) :: info
     INTEGER, OPTIONAL, INTENT(OUT) :: ierror
.ft P
.fi
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.SH INPUT PARAMETERS
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.IP \(bu 2
\fBcomm\fP: Communicator on which to set info hints
.IP \(bu 2
\fBinfo\fP: Info object containing hints to be set on \fIcomm\fP
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.SH OUTPUT PARAMETERS
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.IP \(bu 2
\fBierror\fP: Fortran only: Error status (integer).
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.SH DESCRIPTION
.sp
\fI\%MPI_Comm_set_info\fP sets new values for the hints of the communicator
associated with \fIcomm\fP\&. \fI\%MPI_Comm_set_info\fP is a collective routine. The
info object may be different on each process, but any info entries that
an implementation requires to be the same on all processes must appear
with the same value in each process’s \fIinfo\fP object.
.sp
The following info key assertions may be accepted by Open MPI:
.sp
\fImpi_assert_no_any_tag\fP (boolean): If set to true, then the
implementation may assume that the process will not use the \fBMPI_ANY_TAG\fP
wildcard on the given communicator.
.sp
\fImpi_assert_no_any_source\fP (boolean): If set to true, then the
implementation may assume that the process will not use the
\fBMPI_ANY_SOURCE\fP wildcard on the given communicator.
.sp
\fImpi_assert_exact_length\fP (boolean): If set to true, then the
implementation may assume that the lengths of messages received by the
process are equal to the lengths of the corresponding receive buffers,
for point\-to\-point communication operations on the given communicator.
.sp
\fImpi_assert_allow_overtaking\fP (boolean): If set to true, then the
implementation may assume that point\-to\-point communications on the
given communicator do not rely on the non\-overtaking rule specified in
MPI\-3.1 Section 3.5. In other words, the application asserts that send
operations are not required to be matched at the receiver in the order
in which the send operations were performed by the sender, and receive
operations are not required to be matched in the order in which they
were performed by the receiver.
.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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.IP \(bu 2
\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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.sp
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.
.sp
\fBSEE ALSO:\fP
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.INDENT 3.5
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.IP \(bu 2
\fI\%MPI_Comm_get_info\fP
.IP \(bu 2
\fI\%MPI_Info_create\fP
.IP \(bu 2
\fI\%MPI_Info_set\fP
.IP \(bu 2
\fI\%MPI_Info_free\fP
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.SH COPYRIGHT
2003-2025, The Open MPI Community
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