Integrated: 8364258: ThreadGroup constant pool serialization is not normalized

[Markus Grönlund]

On Wed, 30 Jul 2025 16:08:59 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

> Greetings,
> 
> The following change set normalizes the ThreadGroup constants being serialized to the .jfr binary file.
> 
> It does this in two parts:
> 
> 1. Re-inserts a scavenging scheme to remove stale (unloaded) ThreadGroups; some logic that we used to have in place, but may have been lost as part of the major refactoring around JFR Event Streaming, or even earlier.
> 2. Introduces a per-epoch "is_serialized" scheme, building on top of JFR epoch generations.
> 
> Problem manifestation is a very high number of duplicated TGs (jdk.types.ThreadGroup) as part of JFR checkpoints.
> 
> Testing: jdk_jfr
> 
> Thanks
> Markus

This pull request has now been integrated.

Changeset: 3bc44979
Author:    Markus Grönlund <mgronlun at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/3bc449797eb59f9770d2a06d260b23b6efd5ff0f
Stats:     938 lines in 12 files changed: 431 ins; 482 del; 25 mod

8364258: ThreadGroup constant pool serialization is not normalized

Reviewed-by: egahlin

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PR: https://git.openjdk.org/jdk/pull/26558