Robert Jacques, el 18 de abril a las 11:56 me escribiste:
> On Sat, 18 Apr 2009 11:24:14 -0400, Leandro Lucarella <llu...@gmail.com>
> wrote:
> >I've just found out[1] this[2]:
> >
> > The garbage collector is not guaranteed to run the destructor for
> > all unreferenced objects.
> >
> >Is there any reason why D can't guarantee that all finalizers will be
> >called, at least when the program ends?
>
> Well, a couple of quick tests show that under normal situations (i.e.
> normal program termination and termination from an exception) the
> finalizers do run (D2). However, if a finalizer throws an exception,
> then the rest of the finalizers aren't called. Also, if you call
> std.c.stdlib.exit, the finalizers won't run.
Well, I'm not talking about experimentation, I'm talking about source code
;)
The current GC implementation don't call finalizers for data that's still
reference when the program *ended* (this is allowed by the specs, so it's
fine, the question is why it's allowed by the specs).
Here is a simple example that demonstrate the case:
$ cat finalize.d
version (Tango)
import tango.stdc.stdio;
else
import std.c.stdio;
class A
{
~this() { printf("term\n"); }
}
A a;
static this() { a = new A; }
void main()
{
version (FREE)
a = null;
}
$ for compiler in dmd dmd2 gdmd; do for version in '' '-version=FREE'; do
$compiler $version finalize.d; echo $compiler $version; ./finalize; echo; done;
done
dmd
dmd -version=FREE
term
dmd2
dmd2 -version=FREE
term
gdmd
gdmd -version=FREE
term
(I have my ldc copy broken right now, that's why I didn't test that
compiler ;)
This can happen behind your back too if some nice non-pointer value in the
stack or static data unfortunately is a valid pointer.
This example shows that:
$ cat finalize2.d
version (Tango)
import tango.stdc.stdio;
else
import std.c.stdio;
class A
{
~this() { printf("term\n"); }
}
size_t x;
void main()
{
A a = new A;
x = cast(size_t) cast(void*) a;
version (FREE)
x = 0;
}
(the results are the same as the previous example)
--
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
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- Que hacés, ratita?
- Espero un ratito...
