From: "Haase, Konstantin" <Konstantin.Haase@...>
Date: 2011-10-04T15:37:59+09:00
Subject: [ruby-core:39913] Re: [Ruby 1.9 - Feature #5392][Open] Symbol GC

How would you ensure identity? Do a search on every Symbol creation? Keep a hash map?

On Oct 3, 2011, at 09:41 , Kurt Stephens wrote:

> 
> Issue #5392 has been reported by Kurt  Stephens.
> 
> ----------------------------------------
> Feature #5392: Symbol GC
> http://redmine.ruby-lang.org/issues/5392
> 
> Author: Kurt  Stephens
> Status: Open
> Priority: Normal
> Assignee: 
> Category: 
> Target version: 
> 
> 
> I looked more into Symbol GC.  The biggest problem is IDs are not VALUEs.  My outburst at RubyConf based on my stupid assumption that they were -- I was trying to attack the problem using WeakRefs.
> 
> If IDs were VALUEs and Symbols were allocated like any other Object, the existing GC mark and root machinery (including C stack root scans), would take care of it, with an additional sweep of the global_symbol lookup tables.
> 
> However, the remaining issue is IDs stored in globals.  No matter what, IDs stored in C globals will need to be rb_gc_register_address(VALUE*) roots -- this means CRuby API/contract changes.
> 
> Adding a standalone ID mark table and a rb_gc_mark_id() function will not fix problem of lone IDs on the C stack.
> 
> What was the original reason to distinguish Symbol IDs from Object VALUEs, besides making lexer tokens simple to map.
> Would changing IDs to be allocated VALUE objects simplify internals anyway?  This change could also allow Anonymous Symbols and Anonymous Methods.
> 
> -- Kurt Stephens
> 
> 
> 
> 
> -- 
> http://redmine.ruby-lang.org
>