From: "Haase, Konstantin" <Konstantin.Haase@...>
Date: 2011-10-07T15:05:04+09:00
Subject: [ruby-core:40019] Re: 2.0 feature questionnaire


On Oct 6, 2011, at 23:02 , Urabe Shyouhei wrote:

> (10/07/2011 02:19 PM), Evan Phoenix wrote:
>>> (10/02/2011 05:34 PM), Jeremy Kemper wrote:
>>>>> |3. MVM, with inter-vm message passing.
>>>>> 
>>>>> I have not decided yet, but since MVM requires incompatible changes to
>>>>> C API, so we might pend it to Ruby 3.0.
>>>> 
>>>> I understand @shyouhei's branch is backward compatible for extensions
>>>> that don't use MVM features.
>>> 
>> 
>> I did quite of work into getting MVM working on Rubinius and ended up
>> stopping development because I can't see how you can rectify it with how
>> most C extensions are written.
>> 
>> Specifically, most extensions use static VALUEs and IDs variables. To make
>> matters worse, extensions commonly store VALUE's for Modules and Classes in
>> static variables without calling rb_global_variable() (This is itself a
>> latent bug that almost no one hits because how the MRI GC works).
>> 
>> Any C extension that uses any static VALUE or ID will crash the whole
>> process very quickly, meaning that most existing C extensions are not
>> compatible with MVM UNLESS they are recoded to remove static VALUEs and IDs.
>> 
>> I haven't seen @shoyuhei's branch in a while, how is this issue dealt
>> with?
> 
> No, it isn't.  MVM-aware extensions shall obey the MVM-safe APIs.
> 
> But MVM-unaware extensions are OK if and only if the whole ruby
> process don't use MVM features at all.  And even if you don't
> touch MVM things, binary compatibility is broken.  Recompilation
> is mandatory for everything.
> 

So, MVM will not be part of 2.0? Cause Matz said breaking even binary compatibility would not be an option...