lua-users home
lua-l archive

Re: About lua_newthread

[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index] [Thread Index]


The problem with this approach is that the thread will never be garbage collected as lua_newthread push a thread handle on the main thread stack.
So at the end of this call, you still have the thread handle on the stack.
I also see that you use the global table to store thread function. Pay attention that if 2 thread have functions with the same name, they will collide. I use same kind of thing for a game, this is my approach for both liveness of thread and local space :
In my Thread constructor :
// master state is my main thread
 ThreadState = lua_newthread( master_state );
 // prevent thread from being garbage collected
 lua_pushvalue( master_state, -1 );
 ThreadReferenceIdentifier = luaL_ref( master_state, LUA_REGISTRYINDEX );
//Create a local environment with a link to global environment via __index metamethod
 lua_newtable( master_state );
 lua_pushvalue( master_state, -1 );
 lua_setmetatable( master_state, -2 ); //Set itself as metatable
 lua_pushvalue( master_state, LUA_GLOBALSINDEX );
 lua_setfield( master_state, -2, "__index" );
 lua_setfenv( master_state, -2 );
 lua_pop( master_state, 1 );
and in the destructor :
luaL_unref( master_state, LUA_REGISTRYINDEX, ThreadReferenceIdentifier );
If you have any questions about it, don't hesitate
Julien Hamaide
Lead Programmer
10Tacle Studios Belgium
Tom Miles a écrit :
Thanks for the speedy response.
>> Can you show us how you initialize your thread??
I am using an approach similar to the one in Game Programming Gems 5, where I have a manager object that controls the main state and dishes out threads when requested. I.e. //
static void CreateThread(State & state)
{
 if (m_MainState == NULL)
 {
 m_MainState = luaL_newstate();
 luaL_openlibs(m_MainState);
 luaL_openlib(m_MainState, "Script", scriptLib, 0);
 }
 state.m_state = lua_newthread(m_MainState);
// save a pointer to the thread manager object in the global table
 // using the new thread's vm pointer as a key
lua_pushlightuserdata(m_MainState, state.m_state); <--- Is this causing a problem?
 lua_pushlightuserdata(m_MainState, &state);
 lua_settable(m_MainState, LUA_GLOBALSINDEX );
}
static void ReleaseThread(State & state)
{
 int stackSize = lua_gettop(m_MainState);
 for (int n=0; n<stackSize; ++n)
 {
// This check should be: lua_isthread() && lua_tothread() == state.m_state
 if (lua_touserdata(m_MainState, n) == state.m_state)
 {
 lua_remove(m_MainState, n);
 break;
 }
 }
// For the time being, set the value of the key (the state we are removing) in our map to be nil
 lua_pushlightuserdata(m_MainState, state.m_state);
 lua_pushnil(m_MainState);
 lua_settable(m_MainState, LUA_GLOBALSINDEX);
// There is also code to close down lua if we have released the last thread here
}
>> If you use a weak value table, the entry will be deleted when the object
>> is collected.
>> Just put "v" in field __mode of the metatable of your table. If you want
>> weak key, just put "k".
As you can see, I am using the globals table, but I suppose I could create a weak table especially for the job instead.
> Tom
> > -----Original Message-----
> *From:* lua-bounces@bazar2.conectiva.com.br
> [mailto:lua-bounces@bazar2.conectiva.com.br]*On Behalf Of* Raymond Jacobs
> *Sent:* 18 May 2006 16:20
> *To:* Lua list
> *Subject:* Re: About lua_newthread
>
> When you are done with a thread (when lua_resume returns and it's
> not a yield), you should remove the thread directly from the
> stack, this will remove the reference to it and it can then be
> garbage collected (its a pain I know =/).
> > another method which I've not yet done but should work, is to
> create a new thread, create a lua reference to it (using lua_ref)
> then pop it off the stack immediately (so it doesn't get buried),
> and later when you are done with it, destroy the reference
> (lua_unref) and that should allow it to be GC'd
> > hope that helps, > > Raymond Jacobs
> Owner,
> Ethereal Darkness Interactive
>
> > On 5/18/06, *mos* <mmosquito@163.com <mailto:mmosquito@163.com>>
> wrote:
>
>
> Hi
>
> in lua5.1 manual:
>
> lua_newthread
> lua_State *lua_newthread (lua_State *L);
> There is no explicit function to close or to destroy a thread.
> Threads are
> subject to garbage collection, like any Lua object
>
> I don't understand this , for example like Npc in a game
>
> function AI()
> while(true) do
> walkto(A)
> walkto(B)
> ...
> walkto(Z)
> end
> end
>
> I bind each npc with a lua_State by lua_newthread
>
> but the npc will die and i should close the lua_State ,
> but I can
> not.
> what can I do ? or some better suggestion ?
>
> Best Regards
> mos
>
>
>

AltStyle によって変換されたページ (->オリジナル) /