MPI_FILE_GET_INFO(3)				     Open MPI				      MPI_FILE_GET_INFO(3)

MPI_File_get_info — Returns a new info object containing values for current hints associated with a file.

SYNTAX
   C Syntax
	  #include <mpi.h>

	  int MPI_File_get_info(MPI_File fh, MPI_Info *info_used)

   Fortran Syntax
	  USE MPI
	  ! or the older form: INCLUDE 'mpif.h'
	  MPI_FILE_GET_INFO(FH, INFO_USED, IERROR)
	       INTEGER FH, INFO_USED, IERROR

   Fortran 2008 Syntax
	  USE mpi_f08
	  MPI_File_get_info(fh, info_used, ierror)
	       TYPE(MPI_File), INTENT(IN) :: fh
	       TYPE(MPI_Info), INTENT(OUT) :: info_used
	       INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETER
       • fh: File handle (handle).

OUTPUT PARAMETERS
       • info_used: New info object (handle).

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

DESCRIPTION
       MPI_File_get_info  returns  a new info object containing all the hints that the system currently associates
       with the file fh. The current setting of all hints actually used by the system related to this open file is
       returned in info_used. The user is responsible for freeing info_used via MPI_Info_free <#mpi-info-free>.

       Note that the set of hints returned in info_used may be greater or smaller than the set of hints passed	in
       to   MPI_File_open  <#mpi-file-open>,  MPI_File_set_view	 <#mpi-file-set-view>,	and  MPI_File_set_info	<#
       mpi-file-set-info>, as the system may not recognize some hints set by the user, and may	automatically  set
       other  hints  that the user has not requested to be set. See the HINTS section for a list of hints that can
       be set.

HINTS
       The following hints can be used as values for the info_used argument.

       SETTABLE HINTS

       • shared_file_timeout: Amount of time (in seconds) to wait for access to the  shared  file  pointer  before
	 exiting with MPI_ERR_TIMEDOUT.

       • rwlock_timeout:  Amount  of  time (in seconds) to wait for obtaining a read or write lock on a contiguous
	 chunk of a UNIX file before exiting with MPI_ERR_TIMEDOUT.

       • noncoll_read_bufsize: Maximum size of the buffer used	by  MPI	 I/O  to  satisfy  read	 requests  in  the
	 noncollective data-access routines.

	 Note:
	    A  buffer size smaller than the distance (in bytes) in a UNIX file between the first byte and the last
	    byte of the access request causes MPI I/O to iterate and  perform  multiple	 UNIX  read()  or  write()
	    calls.  If	the request includes multiple noncontiguous chunks of data, and the buffer size is greater
	    than the size of those chunks, then the UNIX read() or write() (made at the MPI I/O level) will access
	    data not requested by this process in order to reduce the total number of write() calls made. If  this
	    is	not  desirable	behavior,  you	should reduce this buffer size to equal the size of the contiguous
	    chunks within the aggregate request.

       • noncoll_write_bufsize: Maximum size of the buffer used by MPI	I/O  to	 satisfy  write	 requests  in  the
	 noncollective data-access routines.

	 See the above note in noncoll_read_bufsize.

       • coll_read_bufsize:  Maximum size of the buffer used by MPI I/O to satisfy read requests in the collective
	 data-access routines.

	 See the above note in noncoll_read_bufsize.

       • coll_write_bufsize: Maximum size of the buffer	 used  by  MPI	I/O  to	 satisfy  write	 requests  in  the
	 collective data-access routines.

	 See the above note in noncoll_read_bufsize.

       • mpiio_concurrency:  (boolean)	controls  whether  nonblocking I/O routines can bind an extra thread to an
	 LWP.

       • mpiio_coll_contiguous: (boolean) controls  whether  subsequent	 collective  data  accesses  will  request
	 collectively contiguous regions of the file.

       NON-SETTABLE HINTS

       • filename: Access this hint to get the name of the file.

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.

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026				      MPI_FILE_GET_INFO(3)
