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](https://docs.oracle.com/javase/specs/jls/se18/html/jls-17.html#jls-17.4.5): _"There is a happens-before edge from the end of a constructor of an object to the start of a finalizer (ยง12.6) for that object."_ ------------- Commit messages: - Merge - Update enqueue() docs, add warnings about still-reachable referent - small tweak to enqueue() - Updates to clear() and enqueue() - updates re: reference clearing - Per slack, 'on a queue' is inconsistent with existing wording - reworked - Update 'remains reachable', per Slack - tweak again - tweak - consistency tweaks - ... and 28 more: https://git.openjdk.org/jdk/compare/cc4b0d92...dfce0dd5 Changes: https://git.openjdk.org/jdk/pull/16644/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16644&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8314480 Stats: 108 lines in 4 files changed: 87 ins; 0 del; 21 mod Patch: https://git.openjdk.org/jdk/pull/16644.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/16644/head:pull/16644 PR: https://git.openjdk.org/jdk/pull/16644
