Index: rubygems.rb
===================================================================
--- rubygems.rb	(revision 6694)
+++ rubygems.rb	(revision 6697)
@@ -8,6 +8,7 @@
 require 'rubygems/rubygems_version'
 require 'rubygems/defaults'
 require 'thread'
+require 'weakref'
 
 module Gem
   class LoadError < ::LoadError
@@ -608,7 +609,14 @@
   # Returns the Gem::SourceIndex of specifications that are in the Gem.path
 
   def self.source_index
-    @@source_index ||= SourceIndex.from_installed_gems
+    begin
+      raise WeakRef::RefError unless @@source_index
+      @@source_index.__getobj__
+    rescue WeakRef::RefError
+      source_index = SourceIndex.from_installed_gems
+      @@source_index = WeakRef.new(source_index)
+      source_index
+    end
   end
 
   ##
Index: rubygems/specification.rb
===================================================================
--- rubygems/specification.rb	(revision 6694)
+++ rubygems/specification.rb	(revision 6697)
@@ -74,9 +74,6 @@
 
     # ------------------------- Class variables.
 
-    # List of Specification instances.
-    @@list = []
-
     # Optional block used to gather newly defined instances.
     @@gather = nil
 
@@ -123,11 +120,6 @@
 
     # ------------------------- Infrastructure class methods.
 
-    # A list of Specification instances that have been defined in this Ruby instance.
-    def self.list
-      @@list
-    end
-
     # Used to specify the name and default value of a specification
     # attribute.  The side effects are:
     # * the name and default value are added to the @@attributes list
@@ -534,7 +526,6 @@
       assign_defaults
       @loaded = false
       @loaded_from = nil
-      @@list << self
 
       yield self if block_given?
 
Index: rubygems/gem_path_searcher.rb
===================================================================
--- rubygems/gem_path_searcher.rb	(revision 6694)
+++ rubygems/gem_path_searcher.rb	(revision 6697)
@@ -12,21 +12,6 @@
 #
 class Gem::GemPathSearcher
 
-  #
-  # Initialise the data we need to make searches later.
-  #
-  def initialize
-    # We want a record of all the installed gemspecs, in the order
-    # we wish to examine them.
-    @gemspecs = init_gemspecs
-    # Map gem spec to glob of full require_path directories.
-    # Preparing this information may speed up searches later.
-    @lib_dirs = {}
-    @gemspecs.each do |spec|
-      @lib_dirs[spec.object_id] = lib_dirs_for(spec)
-    end
-  end
-
   # 
   # Look in all the installed gems until a matching _path_ is found.
   # Return the _gemspec_ of the gem where it was found.  If no match
@@ -48,27 +33,25 @@
   # only that there is a match.
   # 
   def find(path)
-    @gemspecs.each do |spec|
-      return spec if matching_file(spec, path)
+    gemspecs.detect do |spec|
+      matching_file(spec, path)
     end
-    nil
   end
 
   private
 
   # Attempts to find a matching path using the require_paths of the
   # given _spec_.
-  #
-  # Some of the intermediate results are cached in @lib_dirs for
-  # speed.
   def matching_file(spec, path)  # :doc:
-    glob = File.join @lib_dirs[spec.object_id], "#{path}#{Gem.suffix_pattern}"
-    return true unless Dir[glob].select { |f| File.file?(f.untaint) }.empty?
+    glob = File.join lib_dirs_for(spec), "#{path}#{Gem.suffix_pattern}"
+    Dir[glob].detect do |file| 
+      File.file?(file.untaint)
+    end      
   end
 
   # Return a list of all installed gemspecs, sorted by alphabetical
   # order and in reverse version order.
-  def init_gemspecs
+  def gemspecs
     Gem.source_index.map { |_, spec| spec }.sort { |a,b|
       (a.name <=> b.name).nonzero? || (b.version <=> a.version)
     }