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

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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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[datadog-official]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 59.09% (-0.04%)

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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	14.68 s	14.70 s	[-0.9%; +0.6%] (no difference)
startup:insecure-bank:tracing:Agent	13.59 s	13.63 s	[-1.2%; +0.6%] (no difference)
startup:petclinic:appsec:Agent	17.08 s	16.82 s	[+0.6%; +2.5%] (maybe worse)
startup:petclinic:iast:Agent	16.95 s	17.05 s	[-1.4%; +0.2%] (no difference)
startup:petclinic:profiling:Agent	16.78 s	16.93 s	[-2.1%; +0.2%] (no difference)
startup:petclinic:sca:Agent	17.01 s	16.70 s	[+1.1%; +2.7%] (significantly worse)
startup:petclinic:tracing:Agent	15.66 s	16.22 s	[-7.6%; +0.8%] (no difference)

Commit: c5c7b38d · 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.