From: Michael Neumann <mneumann@...>
Date: 2004-10-24T08:51:11+09:00
Subject: [BUG] Strange weak-ref behaviour

Hi. Take a look at the source code at the end of the email and run it.
The expected output for me is, either an empty string ("") or nothing
(and this up to 1000 times).  But, the output I get (on both Ruby 1.8.x
and 1.9) is like that shown below:

  "w.rb:16:in `_id2ref'"
  ["w.rb:16:in `_id2ref'", "w.rb:16:in `each_object'", "w.rb:14:in
  `each'", "/home/mneumann/usr/lib/ruby/1.9/set.rb:193:in `each_key'",
  "/home/mneumann/usr/lib/ruby/1.9/set.rb:193:in `each'", "w.rb:14:in
  `each_object'", "w.rb:30"]
  "w.rb:16:in `_id2ref'"
  "/home/mneumann/usr/lib/ruby/1.9/set.rb:193:in `each'"
  "/home/mneumann/usr/lib/ruby/1.9/set.rb:193:in `each_key'"
  "w.rb:14:in `each'"
  #<RangeError: 0x4086550 is recycled object>
  ["w.rb:16:in `_id2ref'", "w.rb:16:in `each_object'", "w.rb:14:in
  `each'", "/home/mneumann/usr/lib/ruby/1.9/set.rb:193:in `each_key'",
  "/home/mneumann/usr/lib/ruby/1.9/set.rb:193:in `each'", "w.rb:14:in
  `each_object'", "w.rb:30"]
  #<RangeError: 0x4084e1c is recycled object>
  "w.rb:14:in `each'"
  "w.rb:14:in `each_object'"
  "w.rb:14:in `each'"
  "w.rb:16:in `_id2ref'"
  "w.rb:14:in `each_object'"
  "w.rb:30"

There must be something wrong, or is this correct? Does Ruby reuse
object_id's? BTW, what happens if an application uses more than 4 billon
(32-bit) objects? Does Ruby fail or reuse old object_ids?

Thanks in advance.

Regards,

  Michael


#################################
# here the code. if no output is shown, try to 
# increase the number of objects registered (1000) 
#
  require 'set'

  class StateRegistry

    def initialize
      @registered_objects = Set.new
    end

    def register(obj)
      @registered_objects.add(obj.object_id)
    end

    def each_object 
      @registered_objects.each do |oid|
        begin
          obj = ObjectSpace._id2ref(oid) 
        rescue RangeError
          next
        end
        yield obj
      end
    end
  end

  s = StateRegistry.new
  1000.times do 
    s.register("")
  end
  ObjectSpace.garbage_collect
  s.each_object {|obj| p obj}