MPI_COMM_SET_INFO(3)				     Open MPI				      MPI_COMM_SET_INFO(3)

MPI_Comm_set_info — Set communicator info hints

SYNTAX
   C Syntax
	  #include <mpi.h>

	  int MPI_Comm_set_info(MPI_Comm comm, MPI_Info info)

   Fortran Syntax
	  USE MPI
	  ! or the older form: INCLUDE 'mpif.h'
	  MPI_COMM_SET_INFO(COMM, INFO, IERROR)
	       INTEGER COMM, INFO, IERROR

   Fortran 2008 Syntax
	  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

INPUT PARAMETERS
       • comm: Communicator on which to set info hints

       • info: Info object containing hints to be set on comm

OUTPUT PARAMETERS
       • ierror: Fortran only: Error status (integer).

DESCRIPTION
       MPI_Comm_set_info sets new values for the hints of the communicator associated with comm. MPI_Comm_set_info
       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
       info object.

       The following info key assertions may be accepted by Open MPI:

       mpi_assert_no_any_tag  (boolean):  If set to true, then the implementation may assume that the process will
       not use the MPI_ANY_TAG wildcard on the given communicator.

       mpi_assert_no_any_source (boolean): If set to true, then the implementation may	assume	that  the  process
       will not use the MPI_ANY_SOURCE wildcard on the given communicator.

       mpi_assert_exact_length	(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.

       mpi_assert_allow_overtaking   (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.

ERRORS
       Almost  all MPI routines return an error value; C routines as the return result of the function and Fortran
       routines in the last argument.

       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 MPI_Init <#mpi-init>/MPI_Init_thread <#mpi-init-thread>,
       after MPI_Finalize <#mpi-finalize>, or when using the Sessions Model  exclusively)  the	error  raises  the
       initial	error  handler.	 The  initial  error  handler can be changed by calling MPI_Comm_set_errhandler <#
       mpi-comm-set-errhandler> on MPI_COMM_SELF when using the World model,  or  the  mpi_initial_errhandler  CLI
       argument	  to   mpiexec	 or   info  key	 to  MPI_Comm_spawn  <#mpi-comm-spawn>/MPI_Comm_spawn_multiple	<#
       mpi-comm-spawn-multiple>.  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.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or  session.  When
	 called on a communicator, it acts as if MPI_Abort <#mpi-abort> was called on that communicator. If called
	 on  a window or file, acts as if MPI_Abort <#mpi-abort> 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.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler	<#mpi-comm-create-errhandler>	  then	   MPI_Comm_set_errhandler	<#
	 mpi-comm-set-errhandler>

       • MPI_File_create_errhandler	 <#mpi-file-create-errhandler>	   then	    MPI_File_set_errhandler	<#
	 mpi-file-set-errhandler>

       • MPI_Session_create_errhandler	 <#mpi-session-create-errhandler>   then   MPI_Session_set_errhandler	<#
	 mpi-session-set-errhandler> or at MPI_Session_init <#mpi-session-init>

       • MPI_Win_create_errhandler	<#mpi-win-create-errhandler>	  then	    MPI_Win_set_errhandler	<#
	 mpi-win-set-errhandler>

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page <#open-mpi> for a full list of MPI error codes <#open-mpi-errors>.

       See the Error Handling section of the MPI-3.1 standard for more information.

       See also:

	  • MPI_Comm_get_info <#mpi-comm-get-info>

	  • MPI_Info_create <#mpi-info-create>

	  • MPI_Info_set <#mpi-info-set>

	  • MPI_Info_free <#mpi-info-free>

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026				      MPI_COMM_SET_INFO(3)
