[sh/8u] RFR 8267561: Shenandoah: Reference processing not properly setup for outside of cycle degenerated GC

[Roman Kennke]

Looks good!

Thanks, Roman


> Shenandoah 8u suffers the same problem as 11u, that could slowly leak 
> heap memory due to not process weak references.
> 
> 11u patch applies cleanly to Shenandoah 8u, however, it does not 
> compile, as APIs are slightly different between 11u and 8u, fixed as 
> follow:
> 
> diff -r 0a4911d2aac7 
> src/share/vm/gc_implementation/shenandoah/shenandoahHeap.cpp
> --- a/src/share/vm/gc_implementation/shenandoah/shenandoahHeap.cpp Tue 
> May 25 13:04:23 2021 -0400
> +++ b/src/share/vm/gc_implementation/shenandoah/shenandoahHeap.cpp Tue 
> May 25 13:27:02 2021 -0400
> @@ -1647,8 +1647,8 @@
>          rp->set_active_mt_degree(_heap->workers()->active_workers());
> 
>          // enable ("weak") refs discovery
> -        rp->enable_discovery(true /*verify_no_refs*/);
> - rp->setup_policy(_heap->soft_ref_policy()->should_clear_all_soft_refs());
> +        rp->enable_discovery(true /*verify_no_refs*/, true);
> + 
> rp->setup_policy(_heap->collector_policy()->should_clear_all_soft_refs());
>        }
> 
> 
> Shenandoah 8u webrev: 
> http://cr.openjdk.java.net/~zgu/JDK-8267561-8u/webrev.00/
> 
> Test:
>   hotspot_gc_shenandoah
> 
> Thanks,
> 
> -Zhengyu
>