problems upgrading from 5.0.3 - 5.1 with lua_newthread luaL_ref lua_gc and lua_resume

[subatomic <kevin@...>]

Hi, I have a small game engine that uses coroutines to run each game
"actor" (NPC) as a lua class which concurently with many other game
actors (think 200+ lua threads)...

My problem is that my threads in 
5.1 are being garbage collected, while in 5.0.3 they are not.
I am using luaL_ref to "save" the thread from being collected until I want it to be, then I use luaL_unref.
This doesn't seem to be working in 
5.1, but worked ok in 5.0.3.
I was wondering if there's a new way to do this now in 5.1, 
or if there is something new about the GC in 5.1 that I don't understand?

My code goes sort of like this:

t = lua_newthread( L );
thread_reference = luaL_ref( L, LUA_REGISTRYINDEX );
      
// then some luabind stuff to construct the new actor script
luabind::object class_constructor_function = luabind::globals(t)[classname];
mMyActor = luabind::call_function<Actor*>( class_constructor_function );
mActorObj = luabind::object( t, mMyActor );

// then push the function and resume the thread for the first time:
mActorObj.push(t);           
lua_pushstring(t, "__call"); 
lua_gettable(t, -2);   
lua_remove(t, -2);    
mActorObj.push(t);      
resume_status = lua_resume(t, 1);

// then garbage collect (we want performance in the game to be predictable as possible)
lua_gc(L,LUA_GCCOLLECT,0);

// then next frame, resume again 
// (here it crashes because 't' has been deleted by lua_gc)
resume_status = lua_resume( t, 0 );


Here
't' has been deleted, I know because I can see 0xfeeefeee's appear inside 't',
which happen when I step over the lua_gc statement...

This did not happen in 5.0.3.  But does happen in 5.1

I
don't want to leave the (many) threads on the stack, in case I overflow
the stack size (my code does work when leaving the thread on the stack, so i know everything else is ok...)...
Any ideas?
thanks!!


(want to play with my code?  see here: http://www.subatomicglue.com/download/luacoroutines.tgz
  note: this version has luaL_ref commented out, so you'd need to put it back to play with it...)

-- 
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