Linus with some good observations on garbage collection

[Brad Roberts]

Also add to it that in many cases you're dealing with a threaded environment, so those refcounts have to be locked
(either via mutexes, or more commonly just atomic) operations which are far more expensive than non-atomic.  More so
when there's actual contention for the refcounted resource.

On 4/22/2011 11:53 AM, Michael Stover wrote:
> This sort of reference count with cyclic dependency detector is how a lot of scripting languages do it, or did it in the
> past.  The problem was that lazy generational GCs are believed to have better throughput in general.
> 
> I'd like to say "were proved" rather than "are believed", but I don't actually know where to go for such evidence.
>  However, I do believe many scripting languages, such as python, eventually ditched the reference counting technique for
> generational, and Java has very fast GC, so I am inclined to believe those real-life solutions than Linus.
> 
> Mike
> 
> On Fri, Apr 22, 2011 at 2:32 PM, Alvaro <alvaro.segura at gmail.com <mailto:alvaro.segura at gmail.com>> wrote:
> 
>     El 22/04/2011 19:36, Walter Bright escribió:
> 
>         http://gcc.gnu.org/ml/gcc/2002-08/msg00552.html
> 
> 
>     I've always been surprised when discussions usually just bring garbage collection as the only alternative to
>     explicit manual memory management. I imagined it as a garbage truck that has its own schedule and may let a lot of
>     trash pile up before passing by. I always naively thought, why not just free immediately when an object gets no
>     references?
> 
>     Not an expert, so there may be reasons I don't see, but now that Linus says somethnig along the lines, I'll ask. Why
>     not? Isn't it much easier to do refcount++ and refcount--, and if refcount==0 immediately "free()"? Memory will be
>     available to other needs faster, no need for an additional thread, or a lot of memory consumed before the advanced
>     garbage truck decides to come in, or slight pauses when collecting trash (maybe only in old implementations), and
>     the implementation is much simpler...
> 
>     OK, I knew about that "cyclic references" problem. But Linus doesn't seem to see a big problem and solutions can be
>     found with care...
> 
>