On Thu, 14 Nov 2024 13:24:26 GMT, Aleksey Shipilev <sh...@openjdk.org> wrote:
>> See the bug for more discussion and reproducer. This PR replaces the ad-hoc >> linked list 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: > > Avoid NPE on empty list, add tests, touchups This seem to handle excessive allocations when churning around an empty list by keeping the head node always allocated. I wonder if there is any worth adding some hysteresis if it churns around a multiple of the `NODE_CAPACITY`, by for example pooling one node. ------------- PR Comment: https://git.openjdk.org/jdk/pull/22043#issuecomment-2476360805
