test: stabilize flaky TestIssue29282

[flaky-claw]

What problem does this PR solve?

Issue Number: close #69824

Problem Summary:
Flaky test TestIssue29282 in pkg/ddl intermittently fails, so this PR stabilizes that path.

What changed and how does it work?

Root Cause

Fixed sleeps let cleanup or cancellation race a still-running background SELECT FOR UPDATE in TestIssue29282.

Fix

NOWAIT verifies the same row-lock behavior before and after rollback without depending on goroutine scheduling.

Verification

Spec:

• target: pkg/ddl :: TestIssue29282
• strategy: tidb.go_flaky.default
• plan mode: BASELINE_ONLY
• requirements: required case must execute; no skip; repeat count = 1
• execution surface: GO_TEST_WITH_TAGS
• build tags: intest, deadlock
• baseline gates: required_flaky_gate, build_safety_gate, intent_guard_gate
• feedback surface source: baseline_only

Observed result:

• status: passed
• required case executed: yes
• submission decision: ALLOWED
• note: Required flaky case executed during validation.
  Required flaky case was not skipped.
  target_flaky passed.
  build passed.
  lint passed.

Gate checklist:

• timing_repro_prefix: SKIPPED
• target_flaky: PASS
• package_scope_raw: SKIPPED
• raw_harness_clarifier: SKIPPED
• build: PASS
• lint: PASS
• external_ci: SKIPPED

Commands:

• go test -json -tags=intest,deadlock ./pkg/ddl -run '^TestIssue29282$' -count=1
• make build
• make lint

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

Fixes #69824

Summary by CodeRabbit

• Tests
  • Updated transaction-locking coverage to verify immediate failure when a row is locked.
  • Added validation that the row becomes accessible after the original transaction rolls back.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign wjhuang2016 for approval. For more information see the Code Review Process.
Please ensure that each of them provides their approval before proceeding.

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Details

Needs approval from an approver in each of these files:

• pkg/ddl/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 3565bec1-f9fa-4006-abb5-0247939fd1bd

📥 Commits

Reviewing files that changed from the base of the PR and between 531e40c and cf9c4c1.

📒 Files selected for processing (1)

• pkg/ddl/db_integration_test.go

---

📝 Walkthrough

Walkthrough

TestIssue29282 replaces goroutine and timeout-based lock blocking validation with explicit FOR UPDATE NOWAIT assertions before and after transaction rollback.

Changes

Lock test validation

Layer / File(s)	Summary
NOWAIT lock checks pkg/ddl/db_integration_test.go	The test asserts that a competing FOR UPDATE NOWAIT fails while the lock is held, then succeeds after rollback and verifies the expected row.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested labels: ok-to-test, approved, lgtm

Suggested reviewers: gmhdbjd, wjhuang2016

Poem

I’m a bunny who watches the lock,
No more waiting around the clock.
NOWAIT says “no,” then rollback says “go,”
The row hops free in a tidy flow.
Test flakes flee—hip-hop, hooray!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: stabilizing flaky TestIssue29282.
Description check	✅ Passed	The description covers the problem, fix, verification, checklist, and links the required issue.
Linked Issues check	✅ Passed	The PR addresses #69824 by removing timing-dependent behavior from TestIssue29282 and stabilizing the flaky test.
Out of Scope Changes check	✅ Passed	The changes stay within the test stabilization scope and do not introduce unrelated code changes.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="Running error: context loading failed: failed to load packages: failed to load packages: failed to load with go/packages: context deadline exceeded"
level=error msg="Timeout exceeded: try increasing it by passing --timeout option"

---

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.5704%. Comparing base (531e40c) to head (cf9c4c1).

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #69881        +/-   ##
================================================
- Coverage   76.3207%   75.5704%   -0.7503%     
================================================
  Files          2041       2084        +43     
  Lines        559975     582360     +22385     
================================================
+ Hits         427377     440092     +12715     
- Misses       131697     140155      +8458     
- Partials        901       2113      +1212     

Flag	Coverage Δ
integration	45.5194% <ø> (+5.8142%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	60.4471% <ø> (ø)
parser	∅ <ø> (∅)
br	63.4209% <ø> (+0.6996%)	⬆️

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