[3AceShowHand]

What problem does this PR solve?

Issue Number: close #6519

What is changed and how it works?

• Detect closing or closed DispatcherManagers before reusing them during bootstrap. Keep bootstrap pending until cleanup completes, then remove the old manager and create a new one through the existing initialization path.
• Record the closing maintainer epoch when a close request is accepted, preserving stale-bootstrap fencing and epoch-0 removal tombstones.
• Add regression coverage for healthy-manager handover, closing/closed-manager recovery, stale epochs, and epoch-0 compatibility and removal.

Check List

Tests

• Unit test

Passed locally:

go test -race -tags=intest ./downstreamadapter/dispatcherorchestrator \
  -run '^TestHandleBootstrapRequest(CanCreateDispatcherAfterHandover|RejectsStaleEpochAfterManagerClose)$' -count=10

go test -race -tags=intest ./downstreamadapter/dispatchermanager ./downstreamadapter/dispatcherorchestrator -count=1

Kafka integration tests were not run.

Questions

Will it cause performance regression or break compatibility?

No performance regression or compatibility break is expected. Changes are limited to bootstrap and close handling. Healthy-manager handover, existing epoch fencing, and epoch-0 compatibility are preserved. No configuration or protocol changes are introduced.

Do you need to update user documentation, design documentation or monitoring documentation?

No documentation updates are needed.

Release note

Fix a changefeed checkpoint stall caused by reusing a closing or closed dispatcher manager after maintainer failover.

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📥 Commits

Reviewing files that changed from the base of the PR and between a45d45f and 224008d.

📒 Files selected for processing: 4

• downstreamadapter/dispatchermanager/dispatcher_manager.go
• downstreamadapter/dispatchermanager/dispatcher_manager_test.go
• downstreamadapter/dispatcherorchestrator/dispatcher_orchestrator.go
• downstreamadapter/dispatcherorchestrator/dispatcher_orchestrator_test.go

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⚙️ Run configuration

• Source mode: Auto
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📥 Commits

Reviewing files that changed from the base of the PR and between 1a9de2d and a45d45f.

📒 Files selected for processing: 4

• downstreamadapter/dispatchermanager/dispatcher_manager.go
• downstreamadapter/dispatchermanager/dispatcher_manager_test.go
• downstreamadapter/dispatcherorchestrator/dispatcher_orchestrator.go
• downstreamadapter/dispatcherorchestrator/dispatcher_orchestrator_test.go

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📝 Walkthrough

The dispatcher manager now reports whether shutdown has started or completed. The orchestrator uses closing state and maintainer epochs when it handles bootstrap and close requests. Added tests cover manager handovers, cleanup, and stale epochs.

Changes: Dispatcher manager handover

Layer / File(s)	Summary
Manager closing state downstreamadapter/dispatchermanager/dispatcher_manager.go, downstreamadapter/dispatchermanager/dispatcher_manager_test.go	Added IsClosing() to report whether the manager is closing or closed. The local fence test checks this state before and after close attempts.
Bootstrap and close handling downstreamadapter/dispatcherorchestrator/dispatcher_orchestrator.go, downstreamadapter/dispatcherorchestrator/dispatcher_orchestrator_test.go	Bootstrap checks maintainer eligibility and attempts to close a closing manager before removing it and continuing. Close handling records the maintainer epoch before attempting to close. Tests cover handovers and stale-epoch requests.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: hongyunyan

Merge Risk: ⚪ Minimal · up to a45d4

The handover can complete after cleanup, and stale requests cannot recreate the old manager. No issue identified here needs resolution before merge.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title names the main change: closed or closing dispatcher managers are rebuilt during maintainer failover, which matches the orchestrator bootstrap changes and the new regression tests. It is spec…
Description check		The description follows the template. It includes the issue link (close #6519), a 'What is changed and how it works' section with three concrete bullets, unit test evidence with exact commands, answer…

Full details: Title check

Explanation

The title names the main change: closed or closing dispatcher managers are rebuilt during maintainer failover, which matches the orchestrator bootstrap changes and the new regression tests. It is specific and short, with no file list or vague terms. The title does not mention the stale-epoch fencing or the close-epoch recording change, but those are secondary.

Full details: Description check

Explanation

The description follows the template. It includes the issue link (close #6519), a 'What is changed and how it works' section with three concrete bullets, unit test evidence with exact commands, answers to both performance/compatibility and documentation questions, and a release note. The Integration test item is not checked, and the summary states that Kafka integration tests were not run. The description does not mention the new IsClosing method, but the required sections are complete.

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_{A rabbit checks the closing gate,
Then waits while cleanup sets things straight.
New epochs find their proper place,
A fresh dispatcher joins the race.
The burrow hums; the handover’s done!}

_{Comment @coderabbitai help to get the list of available commands.}

[3AceShowHand]

/test all

[3AceShowHand]

/test all

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lidezhu, wk989898

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [lidezhu,wk989898]

Approvers can indicate their approval by writing /approve in a comment
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2026-10-23 08:16:56.016709631 +0000 UTC m=+103753.508421880: ☑️ agreed by lidezhu.
• 2026-10-23 08:59:13.37702712 +0000 UTC m=+106290.868739378: ☑️ agreed by wk989898.

[3AceShowHand]

/retest

[3AceShowHand]

/retest

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #6714.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-nextgen-202609: #6715.