oracular (3) MPI_Win_lock_all.openmpi.3.gz

NAME

       MPI_Win_lock_all - Starts an RMA access epoch locking access to all processes in the window

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Win_lock_all(int assert, MPI_Win win)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_WIN_LOCK_ALL(ASSERT, WIN, IERROR)
            INTEGER ASSERT, WIN, IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Win_lock_all(assert, win, ierror)
            INTEGER, INTENT(IN) :: assert
            TYPE(MPI_Win), INTENT(IN) :: win
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

       assert    Program assertion (integer).

       win       Window object (handle).

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       Starts  an  RMA  access  epoch  to  all processes in win, with a lock type of MPI_LOCK_SHARED. During the
       epoch, the calling process can access the window memory on all processes in win by using RMA  operations.
       A  window  locked  with  MPI_Win_lock_all  must  be unlocked with MPI_Win_unlock_all. This routine is not
       collective — the ALL refers to a lock on all members of the group of the window.

       Locks are used to protect accesses to the locked target window effected by RMA calls issued  between  the
       lock  and unlock call, and to protect local load/store accesses to a locked local window executed between
       the lock and unlock call.  Accesses that are protected by an exclusive lock will not be concurrent at the
       window  site  with other accesses to the same window that are lock protected. Accesses that are protected
       by a shared lock will not be concurrent at the window site with accesses protected by an  exclusive  lock
       to the same window.

       The assert argument is used to provide assertions on the context of the call that may be used for various
       optimizations. (See Section 6.4.4 of the MPI-2 Standard.) A value of assert = 0 is always valid.

NOTES

       In a client/server environment in which clients connect to a server and create windows that span both the
       client  and  the  server,  if  a  client  or  server  that  has obtained a lock on such a window and then
       terminates abnormally, the server or other clients may hang in a MPI_Win_lock_all call, failing to notice
       that the peer MPI job has terminated.

ERRORS

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

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO

       MPI_Win_unlock_all MPI_Win_lock