From: Laurent Sansonetti <laurent.sansonetti@...>
Date: 2008-02-29T05:36:22+09:00
Subject: Re: [ANN] MacRuby

On Thu, Feb 28, 2008 at 2:34 AM, Charles Oliver Nutter
<charles.nutter@sun.com> wrote:
> Laurent Sansonetti wrote:
>  > Hi,
>  >
>  > I am honored to announce the beginning of the MacRuby project!
>  >
>  > MacRuby is a version of Ruby that runs on top of Objective-C. More
>  > precisely, MacRuby is currently a port of the Ruby 1.9 implementation
>  > for the Objective-C runtime and garbage collector.
>
>  How are you able to implement ObjectSpace without any impact at runtime?

Because all objects are being allocated from the same memory zone, so
I just have to walk through the zone.

(See /usr/include/malloc/malloc.h for more details.)

>  Do you disable the GC while ObjectSpace is walking? If not, how do you
>  avoid the possibility that objects may be collected while you are
>  walking the heap?

I have been thinking of this too, it appears that the current code
path works well even if a collection occurs right in the middle.

I could nevertheless lock the GC during #each_object if there is a
problem. It doesn't change the fact that there is no runtime penalty
by default (you can use ObjectSpace if you want). Obviously, MacRuby's
#each_object is slower, definitely because it returns all objects from
the zone, including Objective-C objects too.

$ ruby -ve "p ObjectSpace.each_object {}"
ruby 1.8.6 (2007-09-24 patchlevel 111) [universal-darwin9.0]
310
$ /usr/local/bin/ruby -ve "p ObjectSpace.each_object {}"
MacRuby version 0.1 (ruby 1.9.0 2008-02-18 revision 0) [i686-darwin9.2.0]
8759
$ /usr/local/bin/ruby -ve "framework 'cocoa'; p ObjectSpace.each_object {}"
MacRuby version 0.1 (ruby 1.9.0 2008-02-18 revision 0) [i686-darwin9.2.0]
48425

Laurent