Fix context propagation for delayed Netty scheduled task by amarziali · Pull Request #12541 · DataDog/dd-trace-java

amarziali · 2026-09-17T07:09:13Z

What Does This Do

Fixes context propagation for delayed Netty scheduled tasks while moving the Netty-specific execution handling out of the generic RunnableFuture advice.

Starting with Netty 4.1.44, ScheduledFutureTask.run() may be called once while a delayed task is being enqueued and again when the delay expires. Activating the task scope during the enqueue-time call consumes the captured continuation, leaving no context available when the task actually executes.

For Netty versions that expose PromiseTask.runTask(), the generic RunnableFuture instrumentation no longer activates context around ScheduledFutureTask.run(). The netty-concurrent instrumentation instead
activates the existing RunnableFuture state around PromiseTask.runTask(), which is the point where the task body actually executes.

Older Netty versions without runTask() continue using the existing generic RunnableFuture.run() Instrumentation.

This approach:

Reuses the existing RunnableFuture -> State context store.
Avoids an additional marker context store.
Avoids polling the task delay.
Avoids depending on advice ordering.
Removes Netty-specific runtime checks from the generic advice.
Supports regular and shaded Netty implementations.

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
Avoid using close, fix, or any linking keywords when referencing an issue
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 · 2026-09-17T07:09:30Z

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-17T09:33:18.373499Z	`b4c1280`	Manual request
🔒 Security Review	✅ Completed 2026-09-17T09:31:33.866957Z	`b4c1280`	Manual request

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datadog-official · 2026-09-17T07:21:58Z

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 59.03% (-0.07%)

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🔗 Commit SHA: b4c1280 | Docs | Give us feedback!}

datadog-official

The new matcher has no Netty bytecode reference. Unsupported versions pass Muzzle validation, so the inverse compatibility task fails and blocks CI.

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_{🤖 Datadog Autotest · Commit 24279fb · What is Autotest? · @DataDog review to ask questions · Any feedback? Reach out in #autotest}

dd-octo-sts · 2026-09-17T07:31:54Z

🟢 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	14.82 s	14.68 s	[+0.1%; +1.9%] (maybe worse)
startup:insecure-bank:tracing:Agent	13.57 s	13.75 s	[-2.2%; -0.5%] (maybe better)
startup:petclinic:appsec:Agent	17.00 s	16.77 s	[-4.9%; +7.6%] (unstable)
startup:petclinic:iast:Agent	17.28 s	17.53 s	[-2.2%; -0.6%] (maybe better)
startup:petclinic:profiling:Agent	17.44 s	16.63 s	[+0.5%; +9.2%] (maybe worse)
startup:petclinic:sca:Agent	17.52 s	17.35 s	[+0.0%; +2.0%] (maybe worse)
startup:petclinic:tracing:Agent	16.48 s	16.60 s	[-1.8%; +0.3%] (no difference)

Commit: b4c1280d · CI Pipeline · Benchmarking Platform UI

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

amarziali · 2026-09-17T07:50:51Z

@DataDog review

amarziali · 2026-09-17T08:00:45Z

@codex review

datadog-official

More details

Netty 4.1.44 and later keep the captured context until runTask() starts. Older Netty versions continue to activate the context in RunnableFuture.run().

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chatgpt-codex-connector · 2026-09-17T08:05:07Z

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Security review completed. No security issues were found in this pull request.

Reviewed commit: a5ba81ce3d

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More details

Regular and shaded delayed tasks retain context at execution time. Older Netty tasks keep the existing run path.

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amarziali · 2026-09-17T09:09:03Z

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chatgpt-codex-connector · 2026-09-17T09:13:27Z

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amarziali · 2026-09-17T09:26:35Z

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chatgpt-codex-connector · 2026-09-17T09:31:32Z

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chatgpt-codex-connector · 2026-09-17T09:33:16Z

Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: b4c1280db6

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sarahchen6

Left a small comment about scope but otherwise looks reasonable to me!

btw - looks like the failing CI jobs can be fixed by adding

testImplementation project(':dd-java-agent:instrumentation:netty:netty-concurrent-4.0')

to dd-java-agent/instrumentation/armeria/armeria-grpc-0.84/build.gradle. Seems like Armeria's use of java-concurrent now depend on NettyPromiseTaskInstrumentation and require netty-concurrent-4.0..... "Armeria’s tests load java-concurrent, which still captures continuations when Netty scheduled tasks are constructed. This PR makes that instrumentation skip ScheduledFutureTask.run(). So, Activation and release now depend on NettyPromiseTaskInstrumentation in netty-concurrent-4.0."

sarahchen6 · 2026-09-18T19:35:32Z

+          : null;
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class, suppress = Throwable.class)


from Codex review and seems reasonable to me - this closes the scope when runTask() returns or throws. Netty subsequently calls setSuccessInternal() or setFailureInternal(), which notify completion listeners. Those callbacks now execute after the scheduling context has been removed. - so it seems like we can lose span context / disconnect traces here

Move scheduled Netty task handling to Netty instrumentation

24279fb

amarziali added the type: refactoring label Sep 17, 2026

amarziali requested review from a team as code owners September 17, 2026 07:09

amarziali added the inst: netty Netty instrumentation label Sep 17, 2026

amarziali requested review from jordan-wong and sarahchen6 and removed request for a team September 17, 2026 07:09

amarziali changed the title ~~Move scheduled Netty task handling to Netty instrumentation~~ Fix context propagation for delayed Netty scheduled task Sep 17, 2026

chatgpt-codex-connector Bot reviewed Sep 17, 2026

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amarziali marked this pull request as draft September 17, 2026 07:28

datadog-official Bot reviewed Sep 17, 2026

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Comment thread ...atadog/trace/instrumentation/netty40/concurrent/NettyScheduledFutureTaskInstrumentation.java Outdated

amarziali added 2 commits September 17, 2026 09:43

redisign

572e99c

correctness and clean up comments

a5ba81c

datadog-official Bot reviewed Sep 17, 2026

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Comment thread ...va/datadog/trace/instrumentation/java/concurrent/runnable/RunnableFutureInstrumentation.java Outdated

use the right guard

3a9cabf

amarziali marked this pull request as ready for review September 17, 2026 08:52

amarziali requested a review from AlexeyKuznetsov-DD September 17, 2026 08:53

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chatgpt-codex-connector Bot reviewed Sep 17, 2026

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Comment thread ...va/datadog/trace/instrumentation/java/concurrent/runnable/RunnableFutureInstrumentation.java Outdated

Make the guard consistent

b4c1280

sarahchen6 approved these changes Sep 18, 2026

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