On Mon, 21 Sep 2026 15:50:01 GMT, Jorn Vernee <[email protected]> wrote:
>> See the JBS issue for the full explanation of the issue. >> >> Now that https://github.com/openjdk/jdk/pull/25315 was integrated, we are >> able to reliably scan for session oops in a frame, and only deoptimize those >> frames where the oop is live. >> >> I ran the `ConcurrentClose` benchmark before and after this patch, and these >> were the results: >> >> >> Before: >> >> Benchmark Mode Cnt Score Error >> Units >> ConcurrentClose.sharedClose avgt 10 10.139 ± 0.416 >> us/op >> ConcurrentClose.sharedClose:closing avgt 10 29.288 ± 1.257 >> us/op >> ConcurrentClose.sharedClose:memorySegmentAccess avgt 10 0.651 ± 0.030 >> us/op >> ConcurrentClose.sharedClose:otherAccess avgt 10 0.478 ± 0.026 >> us/op >> >> After: >> >> Benchmark Mode Cnt Score Error >> Units >> ConcurrentClose.sharedClose avgt 10 9.860 ± 0.387 >> us/op >> ConcurrentClose.sharedClose:closing avgt 10 28.641 ± 1.175 >> us/op >> ConcurrentClose.sharedClose:memorySegmentAccess avgt 10 0.470 ± 0.013 >> us/op >> ConcurrentClose.sharedClose:otherAccess avgt 10 0.468 ± 0.015 >> us/op >> >> >> We can see that now the unrelated memory access in `memorySegmentAccess` is >> no longer being affected by a scope being closed in another thread. >> >> Testing: `jdk_foreign` suite, and I repeat ran >> `java/foreign/TestHandshake.java` 50 times as well, which is our stress test >> for shared scopes. >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > Jorn Vernee has updated the pull request incrementally with one additional > commit since the last revision: > > Avoid accidental deopts due to scope closure in warmup Overall, looks good. Minor comments follow. src/hotspot/share/prims/scopedMemoryAccess.cpp line 120: > 118: } > 119: > 120: static frame get_last_frame(JavaThread* jt, RegisterMap* register_map) { Nit: why is it a pointer and not a reference? src/hotspot/share/prims/whitebox.cpp line 1770: > 1768: WB_END > 1769: > 1770: WB_ENTRY(jboolean, WB_HasScopedAccess(JNIEnv* env, jobject o, jobject > method)) Have you considered exposing `has_scoped_access` bit through `jdk.test.whitebox.code.NMethod` and `WB_GetNMethod`? ------------- PR Review: https://git.openjdk.org/jdk/pull/30926#pullrequestreview-5295029801 PR Review Comment: https://git.openjdk.org/jdk/pull/30926#discussion_r4085812002 PR Review Comment: https://git.openjdk.org/jdk/pull/30926#discussion_r4085879373
