void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {

  {- -------------------------------------------
  (1) _safepoint_stats[_cur_stat_index] に入っている統計情報を更新する.
      ---------------------------------------- -}

      SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];

      // Record how long spent in cleanup tasks.
      spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;

      cleanup_end_time = end_time;
    }