Re: Re: my garbage collector sucks

Paul Prescod wrote:
> It is probably not a deciding factor, but if you put performance
> aside, reference counted languages can make guarantees about object
> finalization that m&s garbage collected languages cannot.

It turns out that is a myth.  As an outcome of the turing halt theorem, you
cannot predict when and on which instruction the count will go to zero for
different program inputs.  The final result turns out to be identical for
ref counting and tracing.

> Clearly reference counts are losing the meme war and have been doing
> so for quite a while, but perhaps when we all run terahertz computers
> reference counts will come back as an implementation technique to
> simplify finalization.

In all the reading I did today the bottom line was that ref counting and
tracing (mark/sweep) have equivalent advantages/disadvantages but in
different situations.

The reason Java and .NET are using tracing has to do with control.  You
cannot change the ref counting algorithm and behavior.  With tracing you can
fine tune the algorithm.  Ref counting has a problem with cascading deletes.
One ref count going to zero can cause an arbitrarily large number of objects
to need to be deleted and cause an arbitraily long pause to the system.