Avoid deadlocks during Windows overlapped cleanup - #9452

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Recent review info

Run configuration

• Source mode: Auto
• Repository: RustPython/RustPython
• Branch: main
• File: .coderabbit.yml
• Commit: b85582d
• Layers: Repository YAML
• Review profile: CHILL
• Plan: Advanced
• Run ID: 01d10392-6278-468a-8175-765ab953702d

Commits

Reviewing files that changed from the base of the PR and between b85582d and d3b25a9.

Files selected for processing: 2

• crates/stdlib/src/overlapped.rs
• extra_tests/snippets/stdlib_asyncio.py

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 9 remain after this review.

Overlapped cleanup now releases locks around cancellation and error reporting. It closes the event handle before reporting unrecognized cancellation errors. A subprocess test checks exit with an unclosed asyncio event loop.

Changes: Overlapped cleanup

Layer / File(s)	Summary
Cancellation cleanup and process-exit coverage crates/stdlib/src/overlapped.rs, extra_tests/snippets/stdlib_asyncio.py	Overlapped::del releases the VM thread lock during cancellation, closes the event handle before reporting unrecognized cancellation errors, and releases the inner mutex before formatting and reporting the error. The asyncio test checks that a subprocess exits successfully within 10 seconds when its event loop remains open.

Priority: Normal

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

Change: Bug fix

Suggested reviewers: youknowone

Merge Risk: Minimal · up to d3b25

The cleanup change removes the identified shutdown deadlock mechanisms and adds a bounded process-exit regression test. No actionable merge-blocking issue was found.

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 with cyclomatic complexity of at least 2. Documentat…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: preventing deadlocks during Windows overlapped cleanup.
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 1 functions across 2 files.

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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