program testFence 

  ! attempt to mimic how far 'occam' code gets before hanging
  use mpi
  implicit none
  integer, parameter:: arraySize=1000, maxFence=12
  integer:: array1(1:arraySize), array2(1:arraySize), temp1, temp2, temp3
  integer(kind=MPI_ADDRESS_KIND):: winSize, iDisp, mDisp
  integer:: iLoop, mLoop, myRank, mpierror, win_1, win_2, bytes, numPEs
  integer:: out, remain

! for how many loops
  integer, parameter:: iLoop0 = 100, mLoop0=1, iLoop1 = 50, mLoop1=900

  call MPI_INIT(MPIerror)
  call mpi_comm_size(mpi_comm_world, numPEs, MPIerror)
  call MPI_COMM_RANK(MPI_COMM_WORLD, myRank, MPIerror)


  ! set where to write output to
  out = 6

  ! create windows
  call mpi_type_size(mpi_integer, bytes, mpierror)
  winSize = size(array1) * bytes
  call mpi_win_create(array1, winSize, bytes, mpi_info_null, mpi_comm_world, win_1, mpierror)
  call mpi_win_create(array2, winSize, bytes, mpi_info_null, mpi_comm_world, win_2, mpierror)
  call mpi_win_fence(0, win_1, mpierror)
  call mpi_win_fence(0, win_2, mpierror)



  if (myRank.EQ.0) then
     iDisp = 0
     do iLoop = 1, iLoop0
        write(*,*) 'iDisp=', iDisp
        call flush(101)
        call mpi_get(temp1, 1, mpi_integer, 1, iDisp, 1, mpi_integer, win_1, mpierror)
        call mpi_win_fence(0, win_1, mpierror)
        mDisp = 0
        do mLoop =1, mLoop0
           write(*,*) 'mDisp=', mDisp
           call mpi_get(temp2, 1, mpi_integer, 1, mDisp, 1, mpi_integer, win_2, mpierror)
           call mpi_win_fence(0, win_2, mpierror)
           mDisp = mDisp + 1
        end do
        iDisp = iDisp + 1
     end do
     write(*,*) 'done all gets: need to balance Fences'
     do remain = 1, (iLoop1-iLoop0)
        call mpi_win_fence(0, win_1, mpierror)
     end do
     do remain = 1, (iLoop1*mLoop1 - iLoop0*mLoop0)
        call mpi_win_fence(0, win_2, mpierror)
     end do
  elseif (myRank.EQ.1) then
     iDisp = 0
     do iLoop = 1, iLoop1
        write(*,*) 'iDisp=', iDisp
        call flush(101)
        call mpi_get(temp1, 1, mpi_integer, 1, iDisp, 0, mpi_integer, win_1, mpierror)
        call mpi_win_fence(0, win_1, mpierror)
        mDisp = 0
        do mLoop =1, mLoop1
           write(*,*) 'mDisp=', mDisp
           call mpi_get(temp2, 1, mpi_integer, 1, mDisp, 0, mpi_integer, win_2, mpierror)
           call mpi_win_fence(0, win_2, mpierror)
           mDisp = mDisp + 1
        end do
        iDisp = iDisp + 1
     end do
     write(*,*) 'done all gets: need to balance Fences'
     do remain = 1, (iLoop0-iLoop1)
        call mpi_win_fence(0, win_1, mpierror)
     end do
     do remain = 1, (iLoop0*mLoop0 - iLoop1*mLoop1)
        call mpi_win_fence(0, win_2, mpierror)
     end do
  end if

  ! free windows
  call mpi_win_free(win_1, mpierror)
  call mpi_win_free(win_2, mpierror)
  call mpi_finalize(mpierror)
end program testFence