Re: Expectations on when GC is called
- From: Saptarshi Guha <saptarshi.guha@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Thu, 6 Mar 2014 10:08:48 -0800
My mistake, my apologies. What the code should have been
> M = function()
> local myObj = createRObject()
> myObj = functionToProtect(myObj)
> mObj = ffi.gc( myObject, functionToUnProtect)
> -- do something
> return nil
But your answer to (2) is what i wanted to know.
Thanks
Saptarshi
On Thu, Mar 6, 2014 at 9:42 AM, Mike Pall <mike-1403@xxxxxxxxxx> wrote:
> Saptarshi Guha wrote:
> > M = function()
> > myObj = createRObject()
> > myObj = functionToProtect(myObj)
> > mObj = ffi.gc( myObject, functionToUnProtect)
> > -- do something
> > return nil
>
> You're writing to global variables. That's not a good idea in
> general.
>
> > So when the lua code returns to C(after the pcall), i call
> >
> > lua_gc(L, LUA_GCCOLLECT, 0);
> >
> > to trigger the GC. I expect the lua GC to run and myObj to be
> collected
> > and
> > functionToUnProtect to be run.
> >
> > However nothing is printed.
>
> Sure, the global keeps the object alive.
>
> > If i repeat steps (1) and (2) again, then it does get collected.
>
> Because the global now holds the new object and the old object is
> no longer anchored.
>
> > 1. Doesn't lua_gc call the GC?
>
> It does. But that's an expensive thing to do. Not something you'd
> want to do after every call.
>
> > 2. If so, do i have expectations on the time bounds or ordering of
> > collections?
>
> Nope.
>
> --Mike
>
>
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