[vinzee]

Summary

Fixes a memory leak in internal metrics when expire_metrics_secs is set. Expired metrics were removed from the registry but stayed in a timeout cache forever, so memory grew with every new set of labels (for example, every new pod in kubernetes_logs). This removes the cache entry when the metric expires.

References

Closes: #26906
Related: #17973, #17313

Vector configuration

Any config with expire_metrics_secs set where labels keep changing, such as kubernetes_logs on nodes with many short-lived pods.

How did you test this PR?

Added a unit test that creates and expires 10 rounds of 100 pod-labeled counters, and checks that the cache is empty after each round. Without the fix the cache grows by 100 entries every round (1000 after 10 rounds) and never shrinks; with it the cache stays empty. All vector-core metrics tests pass.

I also ran Vector with a file source (include_file_tag: true, expire_metrics_secs: 5) while a script created and deleted 60,000 log files over 10 minutes:

	Memory growth during label churn (over 10 min)	Memory growth after label churn
Vector 0.58.0 (without fix)	keeps growing, to ~230 MiB	stays at ~200 MiB
With fix	stays at ~100 MiB	drops to 69 MiB

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on our guidelines.
• No. A maintainer will apply the no-changelog label to this PR.

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[chatgpt-codex-connector]

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-27T17:57:39.831596Z	ccb2de9	PR opened

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[datadoghq-integration]

More details

Timeout-cache entries are removed only after successful metric expiration, with the recency lock released before cache cleanup.

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