[BUG] thread/sync.rb memory corruption

i'm using ef (electric fence) to show the memory corruption in this script.
to cause it corrupt memory use

   CORRUPT=true ef ruby bug.rb

file: bug.rb

     require 'sync'

     class A
       def initialize
         extend Sync_m
         @observers = []
       end
       def meth
         synchronize(:EX){
           @observers.each do |o|
             if ENV['CORRUPT']
               o.notify nil
             else
               o.notify
             end
           end
         }
       end
       def add_observer o
         synchronize(:EX){
           @observers << o
         }
       end
     end

     class B
       def initialize a
         @a = a
         @a.add_observer self
       end
       def notify *a
         Thread.new{ @a.meth }
       end
     end

     a = A.new
     b = B.new a
     a.meth
     STDIN.gets


note that it is the simple passing, or not, of arguments to the notify method
which triggers the bug.  perhaps this will yield some hints.


regards.

-a
-- 
suffering increases your inner strength.  also, the wishing for suffering
makes the suffering disappear.
- h.h. the 14th dali lama