RFR: 8256011: Shenandoah: Don't resurrect finalizably reachable objects [v2]

Aleksey Shipilev shade at openjdk.java.net
Sun Nov 8 10:32:59 UTC 2020


On Sun, 8 Nov 2020 10:03:07 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> In the weak-LRB we currently return referents when it is 'marked', that is when it's either reachable strongly or through a finalizable object. This means a finalizable object can be resurrected by Reference.get(), which is wrong. Only truly strongly reachable objects should be returned by Reference.get() during weak-reference-processing. 
>> 
>> Testing: hotspot_gc_shenandoah, tier1 & tier2 with -XX:+UseShenandoahGC
>
> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simplify condition, don't resurrect finalizably reachable objects even on phantom access

This makes sense, thanks.

src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp line 105:

> 103: inline oop ShenandoahBarrierSet::load_reference_barrier(oop obj, T* load_addr) {
> 104: 
> 105:   // Prevent resurrection of unreachable non-strorg references.

Have a chance to fix the typo, `non-strong` here?

-------------

Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1109


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