Walkthrough

A new __reduce__ method is added to the SemLock class in the multiprocessing module. This method raises a TypeError to prevent direct pickling of SemLock objects, requiring users to use the appropriate multiprocessing.SemLock wrapper for serialization support instead.

Changes

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Possibly related PRs

• RustPython/RustPython#6542: Modifies the core SemLock implementation in multiprocessing module; this PR complements it by adding pickle prevention via the __reduce__ method.

Poem

🐰 A lock that cannot be pickled sweet,
No brines nor jars shall make it neat,
For SemLock stays locked away,
Wrap it well, the proper way! 🔒

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Review profile: CHILL

Plan: Pro

Reviewing files that changed from the base of the PR and between 609dbb1 and 5697ab3.

• Lib/test/test_concurrent_futures/test_process_pool.py is excluded by !Lib/**

• crates/stdlib/src/multiprocessing.rs

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

**/*.rs: Follow the default rustfmt code style using cargo fmt to format Rust code
Always run clippy to lint code (cargo clippy) before completing tasks and fix any warnings or lints introduced by changes
Follow Rust best practices for error handling and memory management
Use the macro system (pyclass, pymodule, pyfunction, etc.) when implementing Python functionality in Rust

Files:

• crates/stdlib/src/multiprocessing.rs

crates/stdlib/src/multiprocessing.rs (1)

550-555: LGTM!

The __reduce__ method correctly prevents direct pickling of SemLock objects by raising a TypeError. This is consistent with CPython's behavior and the existing _rebuild classmethod design pattern—the higher-level multiprocessing.synchronize.SemLock wrapper is expected to handle serialization while using _rebuild for reconstruction.

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ran 10 times, no problem