On GitHub's Windows 11 ARM64 runner (no GPU, so wgpu uses Microsoft's WARP)
tests/view.rs died with STATUS_ACCESS_VIOLATION in about 1 run in 4. A crash
dump puts it inside WARP's pixel-shader JIT
(d3d10warp!PixelJitProgram::ClassifyVars, on WARP's own thread pool) when the
two tests that render pixels compile shaders on separate devices at once.
Single-threaded, or each test alone, it never crashed (180 runs); bigger
thread stacks didn't help (6/30 vs 7/30), so it's that race, not our code.
The app has one device on a real GPU and can't hit it.
Those two tests now hold a per-binary lock for their whole run (taken before
the harness, so released after its device drops). Other test binaries render
from at most one test.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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