Ilmari Heikkinen
9/25/2007 4:12:00 PM
On 9/25/07, ara.t.howard <ara.t.howard@gmail.com> wrote:
>
> i don't think i've ever noticed this behaviour:
>
> cfp:~ > cat a.rb
>
> class C
> def self.count
> c = 0
> ObjectSpace.each_object do |object|
> c += 1 if self === object rescue next
> end
> c
> end
> end
>
> loop do
> c = nil ### try with and without this!!!!!!!!!!!!!!
>
> (2 ** 16).times do
> c = C.new
> object_id = c.object_id
> ObjectSpace.define_finalizer(c){ :nothing }
> end
>
> puts "before: #{ C.count }"
>
> GC.start
>
> puts "after: #{ C.count }"
> puts
> end
>
>
>
> run both ways. notice that, without the prior declaration of c, the
> code leaks like crazy: the finalizer itself holds a reference to the
> object and prevents it being reaped. i don't think i've ever noticed
> this behavior before. i understand it - but can this be correct? it
> seems like you should be able to define a finalizer on any object
> without preventing it from being gc'd!
The usual way to do finalizers is
class C
def self.finalize(resource)
lambda{ resource.free }
end
def initialize
@resource = Resource.new
ObjectSpace.define_finalizer(self, C.finalize(resource))
end
end
You can't GC the finalizer proc before running it, and you can't
run it if there's a reference to the finalized object somewhere.
Including the finalizer proc.