[gclist] Re: "This Old Space", with apologies to Will Clinger

[Giuliano Carlini]

> Let me repeat Henry's caveat:  Real world heaps have statistics
> very different from those of the radioactive decay model.  The
> radioactive decay model is primarily useful for Gedanken
> experiments that improve our theoretical understanding of
> generational garbage collection.

I don't understand what is useful about a "theoretical
understanding" that is built upon a false premise.

You can't apply a theory to a problem which
violates the theory's premise. Almost all programs
violate the radioactive decay model of object
lifetimes. So the theory tells us nothing about
the behavior of GC's in almost all programs.

On the flip side, we often assume premises we
know to be false because they make problems
easier to solve and because they are a close
enough aproximation (E.g Newtonian mechanics).

The radioactive decay model is definitely
tractable. But is it a close aproximation
to reality? I had thought that Paul Wilson
had pretty conclusively demonstrated that
it is not.

g