From: Robert Klemme <shortcutter@...>
Date: 2013-03-19T02:33:17+09:00
Subject: Re: Copy-on-write

On Mon, Mar 18, 2013 at 6:13 PM, Robert Jackson <robert.w.jackson@me.com> wrote:
>
> On Mar 18, 2013, at 12:03 PM, Robert Klemme <shortcutter@googlemail.com> wrote:
>
>> It sounds as if you were mixing OS and Ruby features.  If the OS
>> implements this *all* processes benefit from it - regardless of
>> implementation.
>
> True, but ruby's garbage collector up until 2.0.0-p0 used a mark and sweep algorithm that completely obviated the capability of COW friendly OS's (because every object was 'written' during each GC run).

Good point!  Maybe Ken was actually wondering about copy on write
friendly Ruby implementations even though the question sounded
different.

> In 2.0.0-p0 the garbage collector is implemented in such a way as to allow copy on write.

Well, pre 2.0 GC does not prevent copy on write - actually it makes
heavy use of copy on write. :-)  I'd rather say that 2.0 GC is "copy
on write friendly" by reducing the amount of memory written during GC
runs.

> Links:
>
> * http://patshaughnessy.net/2012/3/23/why-you-should-be-excited-about-garbage-collection-in-ruby-2-0
> * http://benhoskin.gs/2013/02/24/getting-to-know-ruby-2-0
> * https://blog.heroku.com/archives/2013/3/6/matz_highlights_ruby_2_0_at_waza

Thanks for those links (especially the first one), Robert!

Kind regards

robert

-- 
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