Reliable shutdown on Windows + lelab --stop#46
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nicolas-rabault merged 3 commits intoJul 6, 2026
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On Windows, stopping LeLab (Ctrl-C / closing the terminal) often leaves the
uvicorn and Vite child processes alive, which keeps port :8000 — and any open
camera handles — held. The next `lelab` then fails to bind, or a camera won't
open because the previous run never released it.
- `lelab --stop`: find and terminate a running LeLab and its child process tree,
freeing the port.
- Clean process-tree teardown on exit (psutil, with a Windows `taskkill /T`
fallback) so the uvicorn/Vite children and their handles are actually released.
- Pre-flight port checks with an actionable message ("…run `lelab --stop` to free
it") instead of an opaque bind error, plus a readiness wait before opening the
browser.
Tests in tests/test_scripts_lelab.py cover the stop / teardown / port-check paths
with mocked psutil + subprocess (no real processes spawned).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Thank you @nobullryder for this contribution.
Here are some changes requests that could improve it.
- The install_signal_handlers override + os._exit(0) path now only
applies on Windows (os.name == "nt"); macOS/Linux keep uvicorn's
native handlers, and timeout_graceful_shutdown=2 is restored so the
prod server gracefully drains as it did before this PR.
- _monitor_processes no longer coerces a clean child exit (0) to exit
code 1; since it's inside the `returncode is not None` branch it can
raise SystemExit(returncode) directly.
- _fail is annotated -> NoReturn, dropping the two unreachable
`raise AssertionError("unreachable")` lines.
- The dev-mode SIGINT/SIGTERM handler just raises SystemExit(0);
teardown is owned solely by _run_dev's `except BaseException`
(also removed the same double pass from _monitor_processes).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Very nice, thank you 🤗
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Problem
On Windows, stopping
lelab(Ctrl-C / closing the terminal) often leaves the uvicorn and Vite child processes alive, which keeps port:8000— and any open camera handles — held. The nextlelabthen fails to bind, or a camera won't open because the previous run never released it.What this does
lelab --stop— finds and terminates a running LeLab and its child process tree, freeing the port.taskkill /Tfallback) so the uvicorn/Vite children and their handles are actually released.lelab --stopto free it") instead of an opaque bind error, plus a readiness wait before opening the browser.Tests
tests/test_scripts_lelab.pycovers the stop / teardown / port-check paths with mockedpsutil+subprocess(no real processes spawned).🤖 Generated with Claude Code