lua的多线程问题，请指教^@^

风舞影天

在Lua的文档中关于Threads有这么一段描述：
  The following function creates a new thread in Lua:
        lua_State *lua_newthread (lua_State *L);
  This function pushes the thread on the stack and returns a pointer to a lua_State that represents this new thread. The new state returned by this function shares with the original state all global objects (such as tables), but has an independent run-time stack.
  Each thread has an independent global environment table. When you create a thread, this table is the same as that of the given state, but you can change each one independently.
最开始看到这段话时我们认为有冲突，第一段说所有的state共享全局对象(写了测试程序，对于lua_set/gettable的LUA_GLOBALSINDEX，所有的state，无论是original state的还是用lua_newthread创建的new thread都是共享的)。但是后一段说每个线程都有一个独立的全局环境表，那么我想这个全局环境表和全局对象应该是分开的，但是我不知道如何去操作(set/get)这个全局环境表(global environment table)，那么，我想对它进行操作，应该如何做呢？谢谢～～～