On Thu, 21 Nov 2024 19:33:01 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 with a new target base due to a > merge or a rebase. The incremental webrev excludes the unrelated changes > brought in by the merge/rebase. The pull request contains 17 additional > commits since the last revision: > > - Merge branch 'master' into JDK-8343704-cleaner-gc > - Improve CleanerGC benchmark > - Check all elements are removable after random test > - Use RandomFactory in test > - Touchups > - Merge branch 'master' into JDK-8343704-cleaner-gc > - Drop --add-exports from the test > - prev is not needed > - Do not need -ea -esa in tests, our testing infra adds them already > - Add the node cache > - ... and 7 more: https://git.openjdk.org/jdk/compare/6697ba50...507401c7 src/java.base/share/classes/jdk/internal/ref/CleanerImpl.java line 316: > 314: // as it is not the same element. This keeps all non-head > 315: // nodes at full capacity. > 316: if (head != phc.node || (phc.index != head.size - 1)) { Creating a local final variable with the value of `head.size - 1` early in this method, and use that throughout (since `head.size - 1` is mentioned in multiple places (as indexing as well as assignment via head.size--) would make it a stable point in the logic. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/22043#discussion_r1854212372
