On Fri, 15 Nov 2024 19:30:06 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: > > prev is not needed src/java.base/share/classes/jdk/internal/ref/CleanerImpl.java line 310: > 308: } > 309: assert phc.node.arr[phc.index] == phc; > 310: assert head.size > 0; I now realize that these assertions in `remove()` won't really "work" because _"exceptions thrown by the cleaning action are ignored"_. :( When the cleaner thread removes the phc (`ref.clean()` in `run()` on L142 -> `list.remove()` on PhantomCleanable L94 ), any `AssertionError`s will get lost in `run()`'s `catch` statement, L144. (There is a related RFE [JDK-8305979 : UncaughtExceptionHandler for Cleaner](https://bugs.openjdk.org/browse/JDK-8305979)) ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/22043#discussion_r1844530605
