begin
  MAX_CONCURRENT = 8

  numTimeSteps = -1

  ;
  ; determine how many time steps from the file...
  ;
  f = addfile("sst8292.nc", "r")
  dimNames = getvardims(f)
  dimSizes = getfiledimsizes(f)
  do i=0, dimsizes(dimNames)-1
    if (dimNames(i).eq."time") then
      numTimeSteps = dimSizes(i)
      break
    end if
  end do
  print("Number of timesteps: " + numTimeSteps)
  delete(f)             ; no longer needed

  startPlotTime = systemfunc("date")

  ;
  ; begin generating plot frames...
  ;
  numPlotsCompleted = 0
  numJobsActive = 0
  do i=0,numTimeSteps-1

    ; don't allow more than MAX_CONCURRENT processes at a time....
    do while (numJobsActive.ge.MAX_CONCURRENT)
      ; check if any tasks have completed; block until something completes...
      pid = subprocess_wait(0, True)
      if (pid.gt.0) then
        numPlotsCompleted = numPlotsCompleted + 1
        numJobsActive = numJobsActive - 1
        break
      end if
    end do

    print("working on frame: " + i)
    command = "ncl contourSST.ncl " + str_get_sq() + "timestep=" + i + str_get_sq() + " >/dev/null"
    pid = subprocess(command)
    numJobsActive = numJobsActive + 1
  end do

  ;
  ; need to wait for all pending jobs to complete...
  ;
  do while (numPlotsCompleted.lt.numTimeSteps-1)
      pid = subprocess_wait(0, True)
      if (pid.gt.0) then
        numPlotsCompleted = numPlotsCompleted + 1
      end if
  end do

  wallClockElapseTime(startPlotTime, "done generating plot frames", 0)

  startAnimateTime = systemfunc("date")
  ;
  ; use Imagemagick to create the animation from the *png frames...
  ; 
  system("convert -delay 100 -loop 0 sst*.png sst.gif")

  wallClockElapseTime(startAnimateTime, "done generating animation", 0)
    
end