On Thu, 24 Jul 2025 12:49:36 GMT, Markus Grönlund <mgron...@openjdk.org> wrote:
> Greetings, > > The following change set addresses the data loss resulting in the assertion > "Missing object ID X in pool jdk.types.Method". > > It involves three components: > > 1. Address a regression introduced by > [JDK-835221](https://bugs.openjdk.org/browse/JDK-8352251). By locating > JFR_ONLY(Jfr::check_and_process_sample_request(thread);) before the > global_poll() in SafepointMechanism::process(), a stacktrace can be captured, > and artifacts tagged, during a safepoint. This breaks an invariant as > artifacts, i.e. methods, can be tagged in the wrong epoch (also a stacktrace > can be stored in the wrong epoch). Must be moved to post global_poll(). > > 2. Retransform/Redefine classes include a non-safe copy of Method trace > flags, leading to stale bits being set onto the new Methods. Method trace > flags need to be copied, but must be done under a safepoint. > > 3. It seems that there has been an increase in the frequency of issuing calls > to InstanceKlass::purge_previous_versions(), making scratch klasses and old > methods disappear before JFR gets the chance to serialize also tagged old > methods. Therefore, we need to ensure that we always tag the latest version > of a Method. > > There is also a cleanup of gratuitous type conversions, from Klass* to > InstanceKlass* in the newly introduced MethodTracing subsystem. > > Testing: jdk_jfr, stress testing > > Thank you > Markus This pull request has now been integrated. Changeset: a3499447 Author: Markus Grönlund <mgron...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/a34994476e8f4783c9f5a83a9c3db63ad605b323 Stats: 303 lines in 24 files changed: 129 ins; 101 del; 73 mod 8356587: Missing object ID X in pool jdk.types.Method Reviewed-by: egahlin ------------- PR: https://git.openjdk.org/jdk/pull/26458
