Avoid repeated controller attribute-key allocation in Spring MVC

[amarziali]

What Does This Do

Cache Spring MVC controller span and continuation attribute keys per runtime controller class, avoiding repeated string construction during synchronous and async request handling.

Both MVC decorators own a ClassValue, using the existing immutable Pair type. No additional helper class or injection entries are needed. Key contents, controller-class selection, span lifecycle, and cached UTF-8 span names are preserved.

Temporary JMH benchmark outside the repository, using the final implementation:

Key-handling path	Allocation before → after	Time before → after
Synchronous	376 B → ≈0 B/op	41.2 → 6.0 ns/op
Async, including controller entry/exit	872 B → ≈0 B/op	116.9 → 23.0 ns/op

Simulated one controller class, warmed caches, and a prepopulated ConcurrentHashMap with 65- and 74-character keys.

Results isolate key handling, not whole-request latency. Savings depend on key length, JVM behavior, and servlet implementation.

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 2026-09-17T14:39:14.038262Z	6af3f1d	PR opened
🔒 Security Review	✅ Completed 2026-09-17T14:41:52.143679Z	6af3f1d	PR opened

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[datadog-prod-us1-5]

More details

The cache uses the same runtime handler class and keeps the same attribute keys for synchronous and asynchronous requests.

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[datadog-prod-us1-5]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 68.82% (+9.73%)

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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	14.81 s	14.68 s	[-0.1%; +1.8%] (no difference)
startup:insecure-bank:tracing:Agent	13.63 s	13.63 s	[-0.6%; +0.7%] (no difference)
startup:petclinic:appsec:Agent	17.11 s	16.91 s	[+0.2%; +2.0%] (maybe worse)
startup:petclinic:iast:Agent	16.95 s	17.01 s	[-1.3%; +0.6%] (no difference)
startup:petclinic:profiling:Agent	16.63 s	16.86 s	[-2.4%; -0.2%] (maybe better)
startup:petclinic:sca:Agent	16.97 s	16.87 s	[-0.3%; +1.5%] (no difference)
startup:petclinic:tracing:Agent	16.17 s	16.03 s	[-0.1%; +1.8%] (no difference)

Commit: 6af3f1d5 · 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.

[ygree]

IDM approved

[amarziali]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-09-18 07:32:20 UTC ℹ️ Start processing command /merge

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2026-09-18 07:32:26 UTC ℹ️ MergeQueue: pull request added to the queue

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

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2026-09-18 08:35:49 UTC ℹ️ MergeQueue: This merge request was merged