ClassValue rooting objects after it goes away?

[Vladimir Ivanov]

Charlie,

Does it look similar to the following bugs?
   https://bugs.openjdk.java.net/browse/JDK-8136353
   https://bugs.openjdk.java.net/browse/JDK-8169425

If that's the same (and it seems so to me [1]), then speak up and 
persuade Paul it's an important edge case (as stated in JDK-8169425).

Best regards,
Vladimir Ivanov

[1] new RubyClass(Ruby.this) in

     public static class Ruby {
         private ClassValue<RubyClass> cache = new ClassValue<RubyClass>() {
             protected RubyClass computeValue(Class<?> type) {
                 return new RubyClass(Ruby.this);
             }
         };

On 3/1/18 2:25 AM, Charles Oliver Nutter wrote:
> So I don't think we ever closed the loop here. Did anyone on the JDK 
> side confirm this, file an issue, or fix it?
> 
> We still have ClassValue disabled in JRuby because of the rooting issues 
> described here and in https://github.com/jruby/jruby/pull/3228.
> 
> - Charlie
> 
> On Thu, Aug 27, 2015 at 7:04 AM Jochen Theodorou <blackdrag at gmx.org 
> <mailto:blackdrag at gmx.org>> wrote:
> 
>     One more thing...
> 
>     Remi, I tried your link with my simplified scenario and it does there
>     not stop the collection of the classloader
> 
>     Am 27.08.2015 11:54, schrieb Jochen Theodorou:
>      > Hi,
>      >
>      > In trying to reproduce the problem outside of Groovy I stumbled
>     over a
>      > case case which I think should work
>      >
>      > public class MyClassValue extends ClassValue {
>      >      protected Object computeValue(Class type) {
>      >          Dummy ret = new Dummy();
>      >          Dummy.l.add (this);
>      >          return ret;
>      >      }
>      > }
>      >
>      >   class Dummy {
>      >       static final ArrayList l = new ArrayList();
>      >   }
>      >
>      > basically this means there will be a hard reference on the ClassValue
>      > somewhere. It can be in a static or non-static field, direct or
>      > indirect. But this won't collect. If I put for example a
>     WeakReference
>      > in between it works again.
>      >
>      > Finally I also tested to put the hard reference in a third class
>      > instead, to avoid this self reference. But it can still not collect.
>      >
>      > So I currently have the impression that if anything holds a hard
>      > reference on the class value that the classloader cannot be collected
>      > anymore.
>      >
>      > Unless I misunderstand something here I see that as a bug
>      >
>      > bye blackdrag
>      >
> 
> 
>     --
>     Jochen "blackdrag" Theodorou
>     blog: http://blackdragsview.blogspot.com/
> 
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> -- 
> 
> - Charlie (mobile)
> 
> 
> 
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