[ruby-talk:04440] Re: Real world performance problems

Aleksi Niemel<[e-mail]> writes:

> But I started to think if there has been any research (probably has :) of
> hybrid of reference counting and pure GCing. So that we always release
> objects when their reference count goes 0, and loops are resolved by normal
> GC. For example the root problem for this thread would have enormous
> advantage, as once used intermediate objects could be reused, and they
> wouldn't have to wait until next mark&sweep.

I've read about hierarchical garbage collection, where objects start
out in a kind of short-term pool, where m&s is very fast. As they age,
they get moved out to a bigger pool.  You collect in the small pool
often, and in the big pool less frequently. The idea is that most
objects are short-lived, and hence never make it to the big pool.

There's also been some work in Java on analyzing program flow to
determine if objects can ever be referenced from outside the current
stack frame. If not, they're allocated on the stack directly, not on
the heap, and hence never have to be garbage collected.

I'd really rather not see us moving to reference counting--one of the
joys of Ruby is the ease with which extensions are written.


Regards


Dave