From: Eric Mahurin <eric_mahurin@...>
Date: 2005-06-21T04:11:32+09:00
Subject: Re: GC.disable not working?

--- Robert Klemme <bob.news@gmx.net> wrote:

> > I have tried Thread.critical= which is what Mutex and
> probably
> > other mutual exclusivity stuff are based on.  The problem
> is
> > that GC/finalizers is not considered to be in separate
> threads.
> 
> But in that case one of the two might help - the one that
> isn't reentrant, 
> would it?

I'll go look at this again.  I all of this had to do with
exclusivity between threads.  If I can do it within one thread,
that may work.

> def testit
>   obj = Object.new
>   ObjectSpace.define_finalizer(obj) {|oid| puts "cleanup
> #{oid}" }
>   obj = nil
> end
> 
> 
> 10.times do
>   1000.times { testit }
>   GC.start
>   sleep 1
> end
> 
> puts "end"

...

> Also, the oids seem not reused (see the sort output).

I find them reused.  I modified your code a little to track
what's been used:

@used = {}

def testit
  obj = Object.new
  id = obj.object_id
  @used[id]==false and puts("reused #{id} after finalizing")
  @used[id] = true
  ObjectSpace.define_finalizer(obj) {|oid|
    #puts "cleanup #{oid}"
    begin
        ObectSpace._id2ref(oid)
        puts("reused #{id} before finalizing!!!!!!!!!!")
    rescue RangeError
    end
    @used[oid] = false
  }
  obj = nil
end

10.times do
  1000.times { testit }
  GC.start
  sleep 1
end


Fortunately, I never see it reuse id's before the object for
that id is finalized.


> A solution to tackle the oid reuse issue (if it's an issue)
> would be to 
> store something that can verify that the oid belongs to the
> data stored for 
> that oid.  Unfortunately I can't think of a way ATM...

That's kind of what WeakRef does.  Unfortunately it is about
20X slower than using simple object ids.  Using GC.start with
object ids is much faster.




		
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