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. The
       following assertion value is supported:

       MPI_MODE_NOCHECK
              No other processes will hold or attempt to acquire a conflicting lock while the caller  holds  the
              window lock.

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  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_thread,   after
       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 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_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 was called on  that  communicator.  If  called  on  a
         window  or file, acts as if 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 then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

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

       See the MPI man page for a full list of MPI error codes.

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

       SEE ALSO:

          • MPI_Win_unlock_all

          • MPI_Win_lock

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                               MPI_WIN_LOCK_ALL(3)