program main
      use MPI
      integer n, myrank, npes, ipid, getpid, ierr
      real(kind=8) :: x
      real(kind=8), allocatable :: a(:)

      call MPI_INIT(ierr)
      call MPI_COMM_RANK(MPI_COMM_WORLD,myrank,ierr)
      call MPI_COMM_SIZE(MPI_COMM_WORLD,npes,ierr)
      ipid = getpid()
      allocate(a(npes+myrank))
      call MPI_BARRIER(MPI_COMM_WORLD, ierr)

      ! fill arbitrary data
      n = npes + myrank
      if (myrank == npes/2) n = n + 1 ! 8-byte overwrite
      do i = 1, n
          a(i) = sqrt(real(i,8))
      end do
      x = a(1) + a(n-1)
      call sleep_(mod(myrank+2,npes))
      call MPI_BARRIER(MPI_COMM_WORLD, ierr)
      deallocate(a)

      ! postfree read
      !if (myrank == 1) x = x + a(2)
      call MPI_BARRIER(MPI_COMM_WORLD, ierr)

      write(*,*) 'mem-debug: x = ', x
      call MPI_BARRIER(MPI_COMM_WORLD, ierr)
      call MPI_FINALIZE(ierr)
      end