Finalization

This page describes the finalization and cleanup phase after the main computation.

Overview

The finalization phase handles:

Final output writing
Memory deallocation
Performance statistics
Cleanup of resources

Main Steps

1. Final Output

Write final state:

subroutine finalize_simulation()

  ! Write final VTK file
  call vtk_output%write_field('h', h)
  call vtk_output%write_field('u', u)
  call vtk_output%write_field('v', v)
  call vtk_output%finalize()

  ! Close CSV files
  call csv_output%close()

  ! Write summary
  call write_summary()

end subroutine finalize_simulation

2. Performance Statistics

Display timing information:

subroutine print_performance()

  if (rank == 0) then
    print *, ''
    print *, '========================================='
    print *, 'Performance Statistics'
    print *, '========================================='
    print *, ''

    ! Total simulation time
    print '(A,F10.2,A)', 'Total time: ', t_total%elapsed(), ' s'
    print *, ''

    ! Breakdown by routine
    print '(A,F10.2,A,F6.2,A)', '  Flux computation: ', &
      t_flux%elapsed(), ' s (', &
      100.0*t_flux%elapsed()/t_total%elapsed(), '%)'

    print '(A,F10.2,A,F6.2,A)', '  Field update: ', &
      t_update%elapsed(), ' s (', &
      100.0*t_update%elapsed()/t_total%elapsed(), '%)'

    print '(A,F10.2,A,F6.2,A)', '  Output writing: ', &
      t_output%elapsed(), ' s (', &
      100.0*t_output%elapsed()/t_total%elapsed(), '%)'

    print *, ''

    ! Performance metrics
    cell_updates = real(mesh%nc, rp) * real(iter, rp)
    print '(A,ES12.3)', '  Cell updates/second: ', &
      cell_updates / t_total%elapsed()

    print *, ''
    print *, '========================================='
  end if

end subroutine print_performance

3. Memory Deallocation

Free all allocated arrays:

subroutine deallocate_fields()

  ! Deallocate field arrays
  if (allocated(h)) deallocate(h)
  if (allocated(u)) deallocate(u)
  if (allocated(v)) deallocate(v)

  ! Deallocate intermediate arrays
  if (allocated(rhs_h)) deallocate(rhs_h)
  if (allocated(rhs_u)) deallocate(rhs_u)
  if (allocated(rhs_v)) deallocate(rhs_v)

  ! Deallocate mesh
  call mesh%deallocate()

  if (rank == 0) then
    print *, 'Memory deallocated successfully'
  end if

end subroutine deallocate_fields

4. Summary Output

Write simulation summary:

subroutine write_summary()
  integer :: unit

  if (rank == 0) then
    open(newunit=unit, file='results/summary.txt', status='replace')

    write(unit, '(A)') '====================================='
    write(unit, '(A)') 'Tolosa-lib Shallow-Water Example'
    write(unit, '(A)') '====================================='
    write(unit, '(A)') ''

    ! Simulation parameters
    write(unit, '(A)') 'Parameters:'
    write(unit, '(A,I0)') '  Number of cells: ', mesh%nc
    write(unit, '(A,I0)') '  Number of MPI processes: ', num_procs
    write(unit, '(A,F8.2)') '  End time: ', t_end
    write(unit, '(A,I0)') '  Iterations: ', iter
    write(unit, '(A)') ''

    ! Physical parameters
    write(unit, '(A)') 'Physical parameters:'
    write(unit, '(A,F8.3)') '  Gravity: ', g
    write(unit, '(A,F8.4)') '  Manning coefficient: ', manning
    write(unit, '(A)') ''

    ! Numerical parameters
    write(unit, '(A)') 'Numerical parameters:'
    write(unit, '(A,F6.3)') '  CFL number: ', cfl
    write(unit, '(A,F10.6)') '  Average dt: ', dt_avg
    write(unit, '(A,A)') '  Scheme: ', trim(scheme_name)
    write(unit, '(A)') ''

    ! Statistics
    write(unit, '(A)') 'Field statistics at final time:'
    write(unit, '(A,F10.4,A,F10.4)') '  h: min=', minval(h), ', max=', maxval(h)
    write(unit, '(A,F10.4,A,F10.4)') '  u: min=', minval(u), ', max=', maxval(u)
    write(unit, '(A,F10.4,A,F10.4)') '  v: min=', minval(v), ', max=', maxval(v)
    write(unit, '(A)') ''

    ! Mass conservation
    write(unit, '(A,ES12.4)') '  Initial mass: ', mass_init
    write(unit, '(A,ES12.4)') '  Final mass: ', mass_final
    write(unit, '(A,ES12.4)') '  Relative error: ', &
      (mass_final - mass_init) / mass_init

    close(unit)

    print *, 'Summary written to results/summary.txt'
  end if

end subroutine write_summary

5. Library Finalization

Clean up Tolosa-lib:

! Finalize MPI
call mpi_finalize_tolosa()

! Finalize library
call tolosa_finalize()

Complete Finalization Routine

subroutine finalize_all()

  ! Write final output
  call write_final_output()

  ! Print performance statistics
  call print_performance()

  ! Write summary file
  call write_summary()

  ! Deallocate memory
  call deallocate_fields()

  ! Finalize timers
  call t_total%finalize()
  call t_flux%finalize()
  call t_update%finalize()
  call t_output%finalize()

  ! Finalize MPI
  call mpi_finalize_tolosa()

  ! Finalize library
  call tolosa_finalize()

  if (rank == 0) then
    print *, ''
    print *, 'Simulation completed successfully!'
  end if

end subroutine finalize_all

Example Output

=========================================
Performance Statistics
=========================================

Total time:      125.34 s

  Flux computation:       98.45 s ( 78.54%)
  Field update:           15.23 s ( 12.15%)
  Output writing:         11.66 s (  9.30%)

  Cell updates/second: 7.98E+06

=========================================

Mass Conservation Check

Verify conservation properties:

function compute_total_mass() result(mass)
  real(rp) :: mass
  integer :: ic

  mass = 0.0_rp
  do ic = 1, mesh%nc
    mass = mass + h(ic) * mesh%cell_vol(ic)
  end do

  ! MPI reduction
  call mpi_allreduce_sum(mass)

end function compute_total_mass

Error Handling

! Check for NaN or Inf
do ic = 1, mesh%nc
  if (isnan(h(ic)) .or. h(ic) /= h(ic)) then
    print *, 'ERROR: NaN detected in h at cell', ic
    print *, 'Time:', t, 'Iteration:', iter
    call tolosa_abort()
  end if
end do

Output Files Generated

After finalization, the following files are created:

results/output_*.vtk - VTK files for visualization
results/gauges.csv - Time series at gauge locations
results/summary.txt - Simulation summary
results/performance.log - Detailed timing statistics

Next Steps

Tolosa-sw Presentation - Full production implementation
Getting Started - Run more Tolosa-lib examples