GC and lua_newthread and other issues

["Wesley Smith" <wesley.hoke@...>]

I'm finding the following behavior a bit odd:

lua_State *Ls = lua_newthread(L);
		printf("\nlua_newthread\n");
		stackDump(L);
		int err = luaL_dofile(Ls, filename);
		if (err) {
			printf("error loading file %s %s\n", filename, lua_tostring(Ls, -1));
			lua_pop(Ls, 2);	//pop error and thread
		}
		else {
			script = new LuaScript(Ls, filename, modDate);
			c_activeScripts[filename] = script;
			
			//register script in Lua to access later and keep from being collected
			lua_getfield(L, LUA_REGISTRYINDEX, LuaAV_app_table_name);
			printf("\n L gut check\n");
			stackDump(L);
			lua_getfield(Ls, LUA_REGISTRYINDEX, LuaAV_app_table_name);
			printf("\n Ls gut check\n");
			stackDump(L);
			lua_pop(L, 1);


output from stackdumps
lua_newthread
stack dump 2:
2 	'thread'
1 table: 0x110b070

 L gut check
stack dump 3:
3 table: 0x110b5a0
2 	'thread'
1 table: 0x110b070

 Ls gut check
stack dump 3:
3 table: 0x110b5a0
2 	'thread'
1 table: 0x110b070

My question is why the second call to lua_getfield doesn't also push a
table (and in fact the same table) on the stack?  This is with Lua
5.1.2.

A further question is about preventing threads from being collected.
I'm pushing the thread created above into a table in the registry but
when I callect the garbage, it goes away.  I've verified that is is
indeed going into the table and the table and the table is in the
registry, but that doesn't seem to stop collection.  Is what I'm
expecting normal behavior?

thanks,
wes