[mpich-discuss] mpi windows with groups mpich2

[Helen Kershaw]

Hi,

I'm trying to use MPI one-sided communication with sub-communicators.
I've put my test code at the end of the email.  It runs on 8 processors, 
creates two communicators, makes a window on the communicators, then 
tries to do some one-sided communication.

I can use groups OR windows without a problem, but when I use them
together (in the test code) I get a coredump from the first 4 tasks.  I
think the one-sided communication may be using the local rank in the 
sub-communicator (mpi_comm_grid) as if it is the global rank in 
mpi_comm_world.

I can run the test code ok using open-mpi, but not mpich2.  I might be
missing something obvious.

Thanks for your help,
Helen

-----
program test_group_win

use mpi

implicit none

! mpi
integer            :: rank, size, ierr, status(mpi_status_size)
! groups
integer, parameter :: group_size = 4
integer            :: group_members(group_size)
integer            :: group_all ! mpi_comm_world group
integer            :: subgroup
integer            :: mpi_comm_grid
integer            :: local_rank ! rank within subgroup


! window
integer                        :: win
integer                        ::bytesize !> size in bytes of each
element in the window
integer(KIND=MPI_ADDRESS_KIND) :: window_size
pointer(aa, duplicate)
real                           :: duplicate(*)
integer(KIND=MPI_ADDRESS_KIND) :: target_disp !> displacement in window
integer                        :: owner
real                           :: result

call mpi_init(ierr)
call mpi_comm_size(mpi_comm_world, size, ierr)
call mpi_comm_rank(mpi_comm_world, rank, ierr)

! create groups
call mpi_comm_group(mpi_comm_world, group_all, ierr)

if (rank < 4 ) then
    group_members = (/0,1,2,3/)
else
    group_members = (/4,5,6,7/)
endif

call mpi_group_incl(group_all, group_size, group_members, subgroup, ierr)
call mpi_comm_create(mpi_comm_world, subgroup, mpi_comm_grid, ierr)
call mpi_comm_rank(mpi_comm_grid, local_rank, ierr) ! rank within group

! create window
call mpi_type_size(mpi_real, bytesize, ierr)
window_size = bytesize ! one element in the window
aa = malloc(1)
call MPI_ALLOC_MEM(window_size, mpi_info_null, aa, ierr)

duplicate(1) = rank

call mpi_win_create(duplicate,  window_size, bytesize, MPI_INFO_NULL,
mpi_comm_grid, win, ierr)

! grabbing data from rank above
if (rank < 3 ) then
    owner = rank + 1
elseif (rank < 7) then
    owner = rank + 1 - 4
else
    owner = 0
endif

print*, 'rank owner', rank, owner

target_disp = 0

call mpi_win_lock(MPI_LOCK_SHARED, owner, 0,  win, ierr)
call mpi_get(result, 1, mpi_real, owner, target_disp, 1, mpi_real, win,
ierr)
call mpi_win_unlock(owner, win, ierr)

print*, 'rank, result ', rank, result

! free window
call mpi_win_free(win, ierr)
call mpi_free_mem(duplicate, ierr)

call mpi_finalize(ierr)

end program test_group_win
----