On Tue, 19 Nov 2024 19:53:45 GMT, Aleksey Shipilev <sh...@openjdk.org> wrote:
>> See the bug for more discussion and reproducer. This PR replaces the ad-hoc >> linked list with segmented list of arrays. Arrays are easy targets for GC. >> There are possible improvements here, most glaring is parallelism that is >> currently knee-capped by global synchronization. The synchronization scheme >> follows what we have in original code, and I think it is safer to continue >> with it right now. >> >> I'll put performance data in a separate comment. >> >> Additional testing: >> - [x] Original reproducer improves drastically >> - [x] New microbenchmark shows no regression on "churning" tests, which >> covers insertion/removal perf >> - [x] New microbenchmark shows improvement on Full GC times (crude, but >> repeatable), serves as a proxy for reproducer >> - [x] `java/lang/ref` tests in release >> - [x] `all` tests in fastdebug > > Aleksey Shipilev has updated the pull request incrementally with one > additional commit since the last revision: > > Use RandomFactory in test src/java.base/share/classes/jdk/internal/ref/PhantomCleanable.java line 55: > 53: * Synchronized by the same lock as the list itself. > 54: */ > 55: CleanerImpl.CleanableList.Node node; I think we can get away with not storing a `Node` in every `PhantomCleanable`, and instead look for it at `index` in each `Node` in the list. But I don't know if this would be a performance win. Heap savings (in `PhantomCleanableRef`)? Worse locality from loading multiple `Nodes`? Just an idea... ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/22043#discussion_r1849349523
