FLT_TEST with MPI, invalid value of ng

[m.hadfield]

When I run the FLT_TEST case with MPI enabled and in debug mode (compiler is G95), it hits an out-of-bounds error in subroutine wclock_on.

The stack trace is

      At line 45 of file timers.f90
Traceback: (Innermost first)
   Called from line 330 of file distribute.f90
   Called from line 262 of file inp_par.f90
   Called from line 94 of file ocean_control.f90
   Called from line 97 of file master.f90
Fortran runtime error: Array element out of bounds: 2 in (1:1), dim=3

The offending line is in subroutine wclock_on (source file timers.f90):

      Cstr(region,MyModel,ng)=my_wtime(wtime)

and the problem is that ng is equal to 2, which is out of bounds for array Cstr. The value of ng = 2 is being passed to this routine by subroutine mp_bcasti_s (file distribute.f90), which is passed it by subroutine inp_par (file inp_par.f90).

Here is the block of code in inp_par where mpi_bcasti_s is called (via the interface mp_bcasti):

!
!-----------------------------------------------------------------------
!  Check C-preprocessing options and definitions.
!-----------------------------------------------------------------------
!
      IF (Master) THEN
        CALL checkdefs
        CALL my_flush (out)
      END IF
      CALL mp_bcasti (ng, model, exit_flag, 1)
      IF (exit_flag.ne.NoError) RETURN

In subroutine inp_par there are several loops of the form

      DO ng=1,Ngrids
        ...
      END DO

but this block of code is not inside one of these loops, so ng is left with the value it had on exit from the previous loop, ie Ngrids+1.

So I presume the solution is to wrap this in a loop

      CALL mp_bcasti (ng, model, exit_flag, 1)

[arango]

Yes, I found this one today too. The logic here is somewhat different since it is independent of nested grid structure. We need to have the following statement instead:

      CALL mp_bcasti (1, model, exit_flag, 1)