Nachos的线程管理模块升级。扩充了线程数据结构。扩展了现有的线程状态。修改了线程调度算法。增加了全局性的线程管理机制。-Nachos thread management module upgrade. Expansion of the thread data structure. Expansion of the existing state of the thread. Amended the thread scheduling algorithm. An increase of the overall management of the thread.