On Wed, 22 Jan 2025 10:52:57 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> wrote:
>> src/java.base/share/classes/jdk/internal/foreign/abi/SharedUtils.java line >> 389: >> >>> 387: @Override >>> 388: protected BufferStack initialValue() { >>> 389: return new BufferStack(Arena.ofAuto().allocate(256)); >> >> Could as well use keep using TerminatingThreadLocal+Unsafe here, I just like >> the fact to use as few non-public apis as possible. > > I'm told that TerminatingThreadLocal runs the "terminate" action for an > object T from the same thread T refers to. So, in principle, using a > TerminatingThreadLocal + confined arena should be ok. > > If that works, I'd suggest to consider maybe moving all this sharing logic > inside BufferStack, so that users only need to do: > > > static final BufferStack LINKER_BUFFER = new BufferStack(256); > > ... > > try (Arena arena = BufferStack.reserve(size)) { > ... > } > > > Which seems a more re-usable API. After all, the fact that we decide to lock > or not in certain cases is heavily influenced by the fact that we expect a > BufferStack to be used with a carrier local, so we might just as well fold > the caching in there. Isn't the problem access? E.g. a virtual thread `A` running on our carrier thread might create the confined arena, binding it to _virtual_ thread `A`, and then another virtual thread `B` comes along one the same carrier thread, and wants to use the same `BufferStack`, but can't because it is confined to thread `A`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/23142#discussion_r1925189099