Reuse Netty request-context attributes between requests

[amarziali]

What Does This Do

Clear HTTP request-context attribute values instead of removing their containers. This avoids recreating attributes and updating Netty’s attribute map on subsequent keep-alive requests.

Adjust HTTP/2 context transfer to ignore empty retained parent attributes while preserving existing child contexts. Channel-close cleanup remains unchanged.

JMH results for the two attribute lifecycles used per request:

Netty	Other attributes	Before → after, ns/op	Before → after, B/op
4.1.112	3	46.8 → 9.8	176 → ~0
4.1.112	11	65.8 → 12.9	304 → ~0
4.1.47	3	24.1 → 12.8	80 → ~0
4.1.47	11	30.2 → 15.9	80 → ~0

Measured using real EmbeddedChannel attributes, 32 rotating context values, JMH 1.37, Temurin 17.0.18, and Apple M4 Max. Three forks, three 1-second warmup iterations, four 1-second measurement iterations, one thread, a 512 MiB heap, and the GC profiler. Timing confidence intervals do not overlap.

Motivation

Additional Notes

Contributor Checklist

• Format the title according to the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any other useful labels
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  Use solves instead, and assign the PR milestone to the issue
• Update the CODEOWNERS file on source file addition, migration, or deletion
• Update public documentation with any new configuration flags or behaviors
• Once approved, use merge queue to merge the PR

Jira ticket: [PROJ-IDENT]

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-21T10:13:00.423663Z	c5c7b38	PR opened
🔒 Security Review	✅ Completed 2026-09-21T10:14:43.143318Z	c5c7b38	PR opened

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[datadog-official]

More details

The change preserves request-context lifecycle behavior while it reuses Netty attribute containers. The static reviewer found no reportable defect in request reuse or HTTP/2 context transfer.

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[dd-octo-sts]

🟢 Java Benchmark SLOs — All performance SLOs passed

Suite	Status
Startup	🟢 pass

SLO thresholds are defined here based on automatically generated metrics. A warning is raised when results are within 5% of the threshold.

PR vs. master results

Scenario	Candidate	master	Δ (95% CI of mean)
startup:insecure-bank:iast:Agent	14.86 s	14.79 s	[-0.5%; +1.4%] (no difference)
startup:insecure-bank:tracing:Agent	13.64 s	13.70 s	[-1.4%; +0.5%] (no difference)
startup:petclinic:appsec:Agent	17.10 s	16.88 s	[+0.4%; +2.2%] (maybe worse)
startup:petclinic:iast:Agent	17.02 s	17.00 s	[-0.6%; +0.9%] (no difference)
startup:petclinic:profiling:Agent	16.74 s	16.93 s	[-2.2%; -0.1%] (maybe better)
startup:petclinic:sca:Agent	17.03 s	16.76 s	[+0.6%; +2.7%] (maybe worse)
startup:petclinic:tracing:Agent	16.10 s	16.13 s	[-1.2%; +0.8%] (no difference)

Commit: eb7603ff · CI Pipeline · Benchmarking Platform UI

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Load and DaCapo benchmarks can be triggered manually in the GitLab pipeline. Results will appear in the Benchmarking Platform UI after completion.

[datadog-official]

More details

Empty parent attributes do not replace child HTTP/2 contexts. Channel-close cleanup still removes all attributes.

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[sarahchen6]

Cool 👍

[ygree]

IDM approved. Left a coupe of notes.

[dd-octo-sts]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-09-23 08:26:24 UTC ℹ️ Start processing command /merge

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2026-09-23 08:26:28 UTC ℹ️ MergeQueue: pull request added to the queue

The expected merge time in master is approximately 1h (p90).

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2026-09-23 09:28:47 UTC ℹ️ MergeQueue: This merge request was merged