From: Robert Klemme <shortcutter@...>
Date: 2007-08-13T18:12:13+09:00
Subject: Re: Interesting garbage collection article on LTU

2007/8/12, Lionel Bouton <lionel-subscription@bouton.name>:
> I just read the abstract on http://lambda-the-ultimate.org/node/2391 and
> found it might be of interest for core language developers and people
> interested in garbage collecting.

Thanks for the link! Will read once I find the time.

> I immediately thought of Ruby because of my experience with long running
> Rails processes. It might be the occasion to have my gut feelings
> checked by people that really know the inner workings of Ruby 1.8 too.
>
> 1/ From my experience the memory usage of a Ruby process never goes down
> (garbage collected objects only free memory for future reallocation, but
> the process memory is never recompacted after garbage collecting).
> 2/ The VM load can remain high after big allocations and subsequent
> garbage collections (ie: there's some pagging going on even if the
> application isn't doing memory intensive operations anymore).

I guess that is one of the core reasons why Java's GC copies objects.
That way you compact the heap and thus ensure that it will sit on less
pages.

> The article above might just have explained to me why Ruby behaves this
> way: the GC might just force paging once the memory footprint of a
> process is large enough, even if most of this process-allocated memory
> is actually free room.
>
> Now going to review the content more in depth.

Kind regards

robert