On Wed, 15 Nov 2023 22:45:46 GMT, Stuart Marks <sma...@openjdk.org> wrote:
>> 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."_ > > src/java.base/share/classes/java/lang/ref/ReferenceQueue.java line 187: > >> 185: * {@link Reference#enqueue()} instead of by the garbage collector, >> its >> 186: * former referent (which has since been cleared) could still be >> strongly >> 187: * reachable. > > See my comments on the corresponding Reference.enqueue() apiNote. I'm not > sure we want to have this issue sprinkled around in the apiNotes for several > methods, including others here on ReferenceQueue. > > If we do want to address this issue -- and it's not clear to me that we do -- > then perhaps we should do it in a central location? We can cover this issue just in `Reference.enqueue()`. I'll take out these `@apiNote`s, and put in `@see Reference.enqueue()`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16644#discussion_r1411395204
