From: "Victor \"Zverok\" Shepelev" <vshepelev@...>
Date: 2006-10-29T05:39:20+09:00
Subject: Re: How to understand why object is not collected?

From: Joel VanderWerf [mailto:vjoel@path.berkeley.edu]
Sent: Saturday, October 28, 2006 11:26 PM
>Victor "Zverok" Shepelev wrote:
>> From: Joel VanderWerf [mailto:vjoel@path.berkeley.edu]
>> Sent: Saturday, October 28, 2006 10:52 PM
>>> This is probably a situation where GC is being conservative. A simple
>>> example:
>>>
>>> class Foo; end
>>>
>>> foo = Foo.new
>>> foo = nil
>>>
>>> GC.start
>>>
>>> p ObjectSpace.each_object(Foo) {}  # ==> 1
>>
>> OK, I've got it.
>>
>>> In my experience, it's hard to write precise unit tests for GC behavior,
>>> and you end up with some fuzziness. The important property of GC is
>>> really the asymptotic behavior.
>>
>> Just for now, I need no precise unit test. I just want to know, would the
>> objects of MyClass collected in principle. Can I achieve the goal
>somehow?
>
>What about creating a lot of them in a loop, without keeping references?
>Then I would expect GC to leave at most one instance.

They can't be created by .new, they created in correspondence to some HTML
DOM by C extension.
Problem already solved by the trick:

--
def test
  span = ....
  ObjectSpace.define_finalizer(span, proc{p "gc ok"})
  span.detach
  span = nil
end

test

GC.start

p "end of code"
--

Output corresponds to my expectations (gc ok => end of code)

Thanks for your help!

V.