Fix `vello_sparse_tests` SIGSEGV when using `cargo test` (#1003)
On some platforms, running the GPU tests in parallel crashes the testing
process more often than not. This "fixes" it for `cargo test` and leaves
`cargo nextest` mostly unimpacted.
```bash
$ cargo test --package vello_sparse_tests
# ...
error: test failed, to rerun pass `-p vello_sparse_tests --test tests`
Caused by:
process didn't exit successfully: `[snip]/vello/target/debug/deps/tests-704ef390c4f325bc` (signal: 11, SIGSEGV: invalid memory reference)
```
diff --git a/sparse_strips/vello_sparse_tests/tests/renderer.rs b/sparse_strips/vello_sparse_tests/tests/renderer.rs
index c610c1d..c3fb50d 100644
--- a/sparse_strips/vello_sparse_tests/tests/renderer.rs
+++ b/sparse_strips/vello_sparse_tests/tests/renderer.rs
@@ -216,7 +216,25 @@
Self::set_transform(self, transform);
}
+ // This method creates device resources every time it is called. This does not matter much for
+ // testing, but should not be used as a basis for implementing something real. This would be a
+ // very bad example for that.
fn render_to_pixmap(&self, pixmap: &mut Pixmap, _: RenderMode) {
+ // On some platforms using `cargo test` triggers segmentation faults in wgpu when the GPU
+ // tests are run in parallel (likely related to the number of device resources being
+ // requested simultaneously). This is "fixed" by putting a mutex around this method,
+ // ensuring only one set of device resources is alive at the same time. This slows down
+ // testing when `cargo test` is used.
+ //
+ // Testing with `cargo nextest` (as on CI) is not meaningfully slowed down. `nextest` runs
+ // each test in its own process (<https://nexte.st/docs/design/why-process-per-test/>),
+ // meaning there is no contention on this mutex.
+ let _guard = {
+ use std::sync::Mutex;
+ static M: Mutex<()> = Mutex::new(());
+ M.lock().unwrap()
+ };
+
let width = self.width();
let height = self.height();
