A render still running on a worker thread while the process exits crashes in the
driver (SIGSEGV in the NVIDIA Vulkan driver on Linux), where neither the panic
hook nor catch_unwind helps: pool workers were detached, the devices are statics
that are never dropped, and nothing on the way out waited for GPU work.
- gpu: every entry into a device (render, device creation, pool trim, denoise
runner and tiles) is counted as work in flight (exit.rs). begin_shutdown()
lets nothing new in; wait_idle(timeout) waits for what is inside.
- preview: JobPool keeps its workers. shutdown(timeout) and Drop discard the
queued jobs and wait, bounded, for the running ones (2 s on drop); never for
the calling thread, and not twice.
- engine: a render job caught by the shutdown gives up instead of rendering on
the CPU, so quitting doesn't wait for it.
- app: on_exit ends with LightcraftApp::shutdown (2 s for everything), after
settings and library are saved; the macOS menu-bar Quit goes through on_exit.
Not changed: the export, merge, denoise and import threads are still detached;
their GPU work goes through the gate, their CPU work is cut off at exit as before.
Tests: pool drop waits / is bounded / survives a panicked job and its own job
dropping it; the gate; GPU renders refused and the device not created after
begin_shutdown; the app's shutdown leaves no render worker. The crash itself
needs Linux + NVIDIA and was not reproduced here (Windows, DX12): 9 of 9 quits
of the app mid-render exit with code 0 in under 0.8 s.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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