Re: calling collectgarbage in __gc metamethod

[Atilim Cetin <atilim.cetin@...>]

On Mon, Aug 6, 2012 at 10:57 PM, Roberto Ierusalimschy
<roberto@inf.puc-rio.br> wrote:
>> I've just met this interesting behavior while writing my Box2d
>> wrapper. I don't know if it's a bug or not but Lua 5.1.4 avoids GC
>> steps while running a __gc metamethod.
>
> The next example calls collectgarbage inside a __gc metamethod without
> any problems (at least in my machine):
>
> -------------------------------
> u = newproxy(true)
> getmetatable(u).__gc = function (o)
>   print("start gc", o)
>   collectgarbage()
>   print("end gc", o)
> end
>
> for i = 1, 10 do
>   u = newproxy(u)
>   print("creating", u)
> end
>
> collectgarbage()
> -------------------------------
>
> So, either you hit a more strange bug in Lua or the crashing is in
> your code.
>
> -- Roberto
>
>

Yes crashing is in my code. In my case, when a __gc metamethod is
called inside another __gc metamethod, my code crashes. Because in the
middle of destruction of one of my objects, another destruction is
initiated.

Here the output is like:
start gc
start gc
start gc
....
end gc
end gc
end gc


But I expected:
start gc
end gc
start gc
end gc
start gc
end gc
....