code: def register_memory():
      
      # XXX How to get a reliable representation of memory being used is
      # not clear. (rss - shared) seems kind of ok but we might also use
      # the private working set via get_memory_maps().private*.
      def get_mem(proc):
          if os.name == 'posix':
              mem = proc.memory_info_ex()
              counter = mem.rss
              if 'shared' in mem._fields:
                  counter -= mem.shared
              return counter
          else:
              # TODO figure out what to do on Windows
              return proc.get_memory_info().rss
  
      if SERVER_PROC is not None:
          mem = get_mem(SERVER_PROC)
          for child in SERVER_PROC.children():
              mem += get_mem(child)
          server_memory.append(bytes2human(mem))
docs: Register an approximation of memory used by FTP server process
      and all of its children.