Release Akka message continuations when discarded to dead letters

[amarziali]

What Does This Do

Release the captured continuation when Akka’s dead-letter queue discards a message envelope.

An actor can terminate while traced messages remain in its mailbox. Akka drains those messages into the dead-letter queue, bypassing ActorCell.invoke() and its normal continuation cleanup.

Changes

• Release the envelope’s continuation after dead-letter handling, including exceptional exits.
• Match MessageQueue implementations nested inside Mailboxes, avoiding reliance on Scala’s anonymous-class numbering.
• Preserve normal actor-message propagation.
• Add deterministic tests for single, multiple and already-wrapped dead-letter messages discarded during termination.

flowchart LR
  A[Capture context in message envelope] --> B{Message disposition}
  B -->|Delivered| C[Actor invokes and closes context]
  B -->|Actor terminates| D[Dead-letter queue]
  D -->|Previously| E[Continuation remains unresolved]
  D -->|Fixed| F[Release captured continuation]
  linkStyle 1,4 stroke:green
  linkStyle 3 stroke:red

Loading

Motivation

This surfaced in the Play 2.5 smoke tests: stream subscription notifications were discarded after their actor stopped, leaving request continuations unresolved.

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 2026-09-23T16:00:59.910718Z	ac09499	PR opened
🔒 Security Review	✅ Completed 2026-09-23T16:03:49.296771Z	ac09499	PR opened

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[datadog-datadog-us1-prod]

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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	14.00 s	13.99 s	[-0.6%; +0.7%] (no difference)
startup:insecure-bank:tracing:Agent	12.96 s	13.06 s	[-1.8%; +0.2%] (no difference)
startup:petclinic:appsec:Agent	17.55 s	17.49 s	[-0.4%; +1.0%] (no difference)
startup:petclinic:iast:Agent	17.44 s	17.61 s	[-1.8%; -0.1%] (maybe better)
startup:petclinic:profiling:Agent	17.43 s	16.71 s	[-0.5%; +9.1%] (no difference)
startup:petclinic:sca:Agent	17.59 s	17.28 s	[+0.9%; +2.7%] (maybe worse)
startup:petclinic:tracing:Agent	16.50 s	16.67 s	[-2.0%; -0.0%] (maybe better)

Commit: 72908d8d · 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.

[amarziali]

/code blockers

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-09-28 07:35:19 UTC ℹ️ Start processing command /code blockers

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2026-09-28 07:35:19 UTC ℹ️ Devflow:

Checking merge blockers for #12616...

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2026-09-28 07:35:28 UTC ℹ️ Devflow: /code blockers

Detected 1 merge blocker(s) to address:

🟠 Pending

• Merge gate rule reviewers-approval is running: 1 approval missing
  All required reviewers must approve this pull request before it can be merged. Learn more in our FAQ.

  • Needs approval from Team: apm-idm-java

  Hint: Questions about this check? Reach out in #dx-source-code-management on Slack.

[amarziali]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-09-28 15:57:38 UTC ℹ️ Start processing command /merge

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2026-09-28 15:57:42 UTC ℹ️ MergeQueue: pull request added to the queue

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

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2026-09-28 16:11:23 UTC ❌ MergeQueue: The build pipeline contains failing jobs for this merge request

Build pipeline has failing jobs for 40ad441:

• build

⚠️ Do NOT retry failed jobs directly (why?).

What to do next?

• Investigate the failures and when ready, re-add your pull request to the queue!
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Details

Since those jobs are not marked as being allowed to fail, the pipeline will most likely fail.
Therefore, and to allow other builds to be processed, this merge request has been rejected and the pipeline got canceled.

[amarziali]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-09-29 06:51:35 UTC ℹ️ Start processing command /merge

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2026-09-29 06:51:40 UTC ℹ️ MergeQueue: pull request added to the queue

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

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2026-09-29 08:05:18 UTC ℹ️ MergeQueue: This merge request was merged