On Tue, 21 Nov 2023 09:08:06 GMT, Viktor Klang <vkl...@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 (§12.6) for that object."_ > > src/java.base/share/classes/java/lang/ref/Reference.java line 405: > >> 403: * <p> This method is invoked only by Java code; when the garbage >> collector >> 404: * clears references it does so directly, without invoking this >> method. The >> 405: * {@link #enqueue} method also clears references directly, without >> invoking > > The last sentence might make sense to have as an apiNote? 🤔 I will remove that sentence here, and instead update the `enqueue()` doc to say that the GC clears and enqueues references without calling `clear()` or `enqueue()`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16644#discussion_r1408644358
