RFR 8209184: JDK8 ResourceBundle vulnerable to GC (fix included)

[mandy chung]

Thanks for the information.  Not sure what's the best option we can do
in 8u.  I think it's acceptable to have a fix that works in the
current context (like empty static method).

Thoughts?

Mandy

On 8/14/18 4:22 PM, Hans Boehm wrote:
> I haven't looked at the details here, but comparing against a volatile 
> is not in general a portable way to keep an object live. Like empty 
> static methods, it may be fine in the current (OpenJDK) context.
> 
> Volatile loads have roach motel semantics and can be advanced past other 
> operations. The comparison can be done early, too, keeping only the 
> condition code. There is no guarantee the reference will still be around 
> when you expect it.
> 
> I haven't come up with a great compiler-independent replacement for 
> reachabilityFence.
> 
> On Tue, Aug 14, 2018 at 8:25 AM mandy chung <mandy.chung at oracle.com 
> <mailto:mandy.chung at oracle.com>> wrote:
> 
>     Hi Adam,
> 
>     Have you tried Peter's suggestion if an empty static method taking an
>     Object parameter?  Does it work for you?
> 
>     Your proposed approach seems fine and I would suggest to put the
>     check in a static keepAlive method that will make it explicitly.
> 
>     Mandy
> 
>     On 8/10/18 8:42 AM, Adam Farley8 wrote:
>      > Hi All,
>      >
>      > This bug could be fixed by comparing the Class Loader with a blank
>      > static volatile Object (defined outside the method scope) at the
>      > end of the getBundleImpl class.
>      >
>      > E.g.
>      >
>      > -----------------------------------------
>      > +1322
>      >      /**
>      >       * volatile reference object to guard the ClassLoader object
>      >       * being garbage collected before getBundleImpl() method
>     completes
>      >       * the caching and retrieving of requested Resourcebundle object
>      >       */
>      >      private static volatile Object vo = new Object();
>      >
>      >
>      > +1400
>      > //Should never be true. Using the loader here prevents it being GC'd.
>      >              if (loader == vo) throw new Error("Unexpected error.");
>      > -----------------------------------------
>      >
>      > Will upload a webrev after debate.
>      >
>      > - Adam
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