current GC behavior

[luka8088]

On 6.11.2012 18:00, Ali Çehreli wrote:
> On 11/06/2012 03:27 AM, luka8088 wrote:
>
>  > I was writing some unit tests and I also wanted to test that in certain
>  > cases object references are properly removed everywhere so that GC can
>  > collect them in order to make sure there is no memory leak. While trying
>  > to achieve this I learned that objects are not always collected at the
>  > time I would expect them to, so I documented current behavior and some
>  > tips.
>
> Thanks for the analysis and the tips but they all depend on observations
> made by a particular test program on a particular version of a
> particular compiler. It is conceivable that even the same GC algorithm
> can behave differently in another program.

Yes, but it seems that we can in general say that the following code 
will never fail... or am I wrong ?

import core.memory;

class a {
   static int totalRefCount = 0;
   this () { totalRefCount++; }
   ~this () { totalRefCount--; }
}

void main () {
   assert(a.totalRefCount == 0);
   ({
     auto a1 = new a();
     assert(a.totalRefCount == 1);
   })();
   GC.collect();
   assert(a.totalRefCount == 0);
}

>
> In fact, some objects may never be collected even if there are no more
> references to them.

Can you give me an example ?

>
> In comparison, destroy() and scoped() do call the destructors at precise
> times.

Yes, but the main reason for doing this is testing for memory leaks so 
this cases are not much of a concern =)

>
> Ali
>

Luka