Bug ID: JDK-8314480 Memory ordering spec updates in java.lang.ref

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JDK 23
23 b26Fixed

Classes in the java.lang.ref package would benefit from an update to bring the spec in line with how the VM already behaves. The changes would focus on happens-before edges at some key points during reference processing.

A couple key things we want to be able to say are:
* Reference.reachabilityFence(x) happens-before reference processing occurs for 'x'.
* Cleaner.register() happens-before the Cleaner thread runs the registered cleaning action. 

This will bring Cleaner in line (or close) with the memory visibility guarantees made for finalizers in JLS 17.4.5[1]:
"There is a happens-before edge from the end of a constructor of an object to the start of a finalizer (§12.6) for that object."

1. https://docs.oracle.com/javase/specs/jls/se18/html/jls-17.html#jls-17.4.5

I just read through the updated Reference.java, and it seems OK to me.

08-06-2024

Changeset: 2cae9a03 Author: Brent Christian <bchristi@openjdk.org> Date: 2024-05-31 21:29:30 +0000 URL: https://git.openjdk.org/jdk/commit/2cae9a0397f4e46c6faec0a998ecad1c7015564d

31-05-2024

A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/16644 Date: 2023-11-13 22:31:16 +0000

13-11-2023

CSR :	JDK-8327707 - Memory ordering spec updates in java.lang.ref
Relates :	JDK-8177915 - Clarify Reference.reachabilityFence use