MPI_GET(3)					     Open MPI						MPI_GET(3)

MPI_Get, MPI_Rget <#mpi-rget> - Copies data from the target memory to the origin.

SYNTAX
   C Syntax
	  #include <mpi.h>

	  MPI_Get(void *origin_addr, int origin_count, MPI_Datatype
	      origin_datatype, int target_rank, MPI_Aint target_disp,
	      int target_count, MPI_Datatype target_datatype, MPI_Win win)

	  MPI_Rget(void *origin_addr, int origin_count, MPI_Datatype
	       origin_datatype, int target_rank, MPI_Aint target_disp,
	       int target_count, MPI_Datatype target_datatype, MPI_Win win,
		   MPI_Request *request)

   Fortran Syntax
	  USE MPI
	  ! or the older form: INCLUDE 'mpif.h'

	  MPI_GET(ORIGIN_ADDR, ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
	      TARGET_DISP, TARGET_COUNT, TARGET_DATATYPE, WIN, IERROR)
	      <type> ORIGIN_ADDR(*)
	      INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP
	      INTEGER ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
	      TARGET_COUNT, TARGET_DATATYPE, WIN, IERROR

	  MPI_RGET(ORIGIN_ADDR, ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
	       TARGET_DISP, TARGET_COUNT, TARGET_DATATYPE, WIN, REQUEST, IERROR)
	       <type> ORIGIN_ADDR(*)
	       INTEGER(KIND=MPI_ADDRESS_KIND) TARGET_DISP
	       INTEGER ORIGIN_COUNT, ORIGIN_DATATYPE, TARGET_RANK,
	       TARGET_COUNT, TARGET_DATATYPE, WIN, REQUEST, IERROR

   Fortran 2008 Syntax
	  USE mpi_f08

	  MPI_Get(origin_addr, origin_count, origin_datatype, target_rank,
		  target_disp, target_count, target_datatype, win, ierror)
	      TYPE(*), DIMENSION(..), ASYNCHRONOUS :: origin_addr
	      INTEGER, INTENT(IN) :: origin_count, target_rank, target_count
	      TYPE(MPI_Datatype), INTENT(IN) :: origin_datatype, target_datatype
	      INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_disp
	      TYPE(MPI_Win), INTENT(IN) :: win
	      INTEGER, OPTIONAL, INTENT(OUT) :: ierror

	  MPI_Rget(origin_addr, origin_count, origin_datatype, target_rank,
	      target_disp, target_count, target_datatype, win, request,
		  ierror)
	      TYPE(*), DIMENSION(..), ASYNCHRONOUS :: origin_addr
	      INTEGER, INTENT(IN) :: origin_count, target_rank, target_count
	      TYPE(MPI_Datatype), INTENT(IN) :: origin_datatype, target_datatype
	      INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) :: target_disp
	      TYPE(MPI_Win), INTENT(IN) :: win
	      TYPE(MPI_Request), INTENT(OUT) :: request
	      INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS
       • origin_addr : Initial address of origin buffer (choice).

       •

	 origin_count (Number of entries in origin buffer (nonnegative)
		integer).

       • origin_datatype : Data type of each entry in origin buffer (handle).

       • target_rank : Rank of target (nonnegative integer).

       •

	 target_disp (Displacement from window start to the beginning of the)
		target buffer (nonnegative integer).

       •

	 target_count (Number of entries in target buffer (nonnegative)
		integer).

       • target datatype : datatype of each entry in target buffer (handle)

       • win : window object used for communication (handle)

OUTPUT PARAMETER
       • request : MPI_Rget <#mpi-rget>: RMA request

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

DESCRIPTION
       MPI_Get	copies	data  from the target memory to the origin, similar to MPI_Put <#mpi-put>, except that the
       direction of data transfer is reversed. The origin_datatype may not  specify  overlapping  entries  in  the
       origin  buffer. The target buffer must be contained within the target window, and the copied data must fit,
       without truncation, in the origin buffer.  Only processes within	 the  same  node  can  access  the  target
       window.

       MPI_Rget	 <#mpi-rget>  is  similar  to MPI_Get, except that it allocates a communication request object and
       associates it with the request handle (the argument  request)  that  can	 be  used  to  wait  or	 test  for
       completion. The completion of an MPI_Rget <#mpi-rget> operation indicates that the data is available in the
       origin buffer. If origin_addr points to memory attached to a window, then the data becomes available in the
       private copy of this window.

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_Put <#mpi-put>

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026						MPI_GET(3)
