plucky (3) MPI_Win_lock_all.openmpi.3.gz
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
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2003-2025, The Open MPI Community
Feb 17, 2025 MPI_WIN_LOCK_ALL(3)