fix: add SIGINT signal handler for reliable Ctrl+C experiment abort

[hhe48203-ctrl]

Summary

• Register a signal.SIGINT handler alongside the existing sys.excepthook to reliably detect Ctrl+C
• sys.excepthook alone fails when the main thread is blocked in C extensions (NumPy, PyTorch, etc.), causing experiments to miss the "aborted" state
• The SIGINT handler calls finish(state="aborted"), restores the original handler, and re-raises the signal for normal process termination
• Handler is properly cleaned up in _cleanup() to avoid leaking into user code after the run ends

Changes

• swanlab/sdk/internal/run/__init__.py: Added _sigint_handler method, SIGINT registration in __init__, and restoration in _cleanup
• tests/unit/sdk/internal/run/test_finish_hook.py: Added 3 test cases covering running state, non-running state, and original callable handler delegation

Testing

• All 10 existing + new unit tests pass
• New tests cover: SIGINT during active run, SIGINT after run finished, original handler forwarding

Fixes #1329

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the robustness of experiment termination in SwanLab by introducing a dedicated SIGINT signal handler. Previously, relying solely on sys.excepthook could lead to experiments failing to register as "aborted" if the main thread was blocked by C extensions (e.g., NumPy, PyTorch). The new handler ensures that Ctrl+C reliably triggers an "aborted" state, improving the accuracy of experiment tracking and providing a more consistent user experience.

Highlights

• Reliable Ctrl+C Abort: Implemented a signal.SIGINT handler to ensure experiments can be reliably aborted via Ctrl+C, addressing limitations of sys.excepthook when the main thread is blocked by C extensions.
• Aborted State Handling: The new SIGINT handler calls finish(state="aborted", error="KeyboardInterrupt") when an experiment is running, marking its state correctly.
• Original Handler Restoration: The handler restores the original SIGINT handler and re-raises the signal to allow for normal process termination.
• Proper Cleanup: The registered SIGINT handler is properly unregistered during the _cleanup() process to prevent leakage into user code.

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Changelog

• swanlab/sdk/internal/run/init.py
  • Imported the signal module.
  • Registered a SIGINT handler in the __init__ method to catch Ctrl+C signals.
  • Implemented the _sigint_handler method to manage the experiment state upon receiving a SIGINT.
  • Ensured the original SIGINT handler is restored during the _cleanup process.
• tests/unit/sdk/internal/run/test_finish_hook.py
  • Imported signal and pytest.
  • Added a new test class TestSigintHandler.
  • Included a test case to verify finish(state='aborted') is called when the experiment is running.
  • Added a test case to confirm no operation when the experiment is not running.
  • Implemented a test case to ensure the original callable handler is invoked.

Activity

• Author implemented a SIGINT handler to address sys.excepthook limitations with Ctrl+C.
• Author added 3 new unit tests covering running state, non-running state, and original handler delegation.
• Author confirmed all existing and new unit tests pass.

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[gemini-code-assist]

Code Review

This pull request introduces a SIGINT signal handler to reliably mark experiments as 'aborted' when interrupted with Ctrl+C. This is a solid improvement, especially for cases where the main thread is blocked in C extensions. The implementation is clean and includes appropriate cleanup and unit tests.

I've found one potential issue in the signal handler's logic concerning how it chains to the original handler, specifically for the SIG_IGN case. I've left a specific comment with a suggested fix. Overall, this is a valuable change that enhances the robustness of the experiment lifecycle management.

[SAKURA-CAT]

LGTM!