When the sub-threading provided a new task, the cylinder number was put into the UP / DOWN mission queue by the main threading according to the disk head direction. And execute the next mission, and save the relevant data into a TXT file. 当子线程产生新柱面请求时,主线程根据磁头运行方向把读取的柱面数赋值到UP/DOWN队列,再执行下一任务,并将相关数据以TXT文件形式存储。