Re: [Vala] use weak and var together

[Hans Vercammen <hveso3 gmail com>]

On Sun, 2009-01-11 at 01:23 +0100, Thomas Chust wrote:
> Hans Vercammen wrote:
> > On Sat, 2009-01-10 at 13:16 -0800, Noah Gibbs wrote:
> > [...]
> > > Remember that an object can be part of more than one cycle, and you
> > > have to know how many of those refs are "cyclic" refs, and how many
> > > (if any) aren't from cycles.  That's non-local knowledge.  What I'm
> > > saying is that it's not an easy think to calculate, and there's a
> > > reason that garbage collectors tend to be slow :-)
> >
> > There are actually rather fast garbage collection algorithms out there.
> > The main reason I can think of why they still appear to be slow is that
> > in most cases they have to "stop the world" to do their processing.
> > [...]
>
> Hello,
>
> there are also real-time garbage collectors that never need to stop the
> program for more than a few microseconds and can run concurrently with
> the main program on a separate thread.
>
> Garbage collection isn't necessarily slow, if it's implemented well. The
> trick is to make the extra work happen concurrently with the main
> program and / or at convenient points in time. Especially if you have a
> lot of memory and can afford to just allocate objects, deferring cleanup
> until the main program is idle, garbage collection is usually faster
> than manual memory management or reference counting which incurs more
> calls to the allocator at inconvenient points in time.

I'm not sure what the actual benefit would be that way. In general I
would agree, but if you mean running the garbage collector in a
different thread; it would imply more synchronization mechanisms, which
would also slow down the process significantly. Not all programs have a
main idle loop or are multi-threaded by default. The main idea of
reference counting is to take care of the object life-cycle immediately
without prosponing it to a different process/thread.

Hans