8356587: Missing object ID X in pool jdk.types.Method

[mgronlun]

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. 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

---

Progress

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Issue

• JDK-8356587: Missing object ID X in pool jdk.types.Method (Bug - P2)

Reviewers

• Erik Gahlin (@egahlin - Reviewer)

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8356587: Missing object ID X in pool jdk.types.Method

Reviewed-by: egahlin

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At the time when this comment was updated there had been 75 new commits pushed to the master branch:

• 70ebb5e: 8364019: Add alignment precondition to Universe::reserve_heap
• b4028c9: 8362482: [TESTBUG] serviceability/HeapDump/UnmountedVThreadNativeMethodAtTop.java: System.gc() does not provide full GC
• 08b0b34: 8361715: (bf) Improve java/nio/Buffer/GetChars.java and migrate to JUnit
• ... and 72 more: https://git.openjdk.org/jdk/compare/15b5b54ac707ba0d4e473fd6eb02c38a8efe705c...master

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• 01: Full - Incremental (a4d6ecc3)
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