Join threads in MULTITHREADED_COMPUTE example.

CHANGELOG.md

@@ -75,6 +75,10 @@ Bottom level categories:
 
 - In Surface::configure and Surface::present, fix the current GL context not being unset when releasing the lock that guards access to making the context current. This was causing other threads to panic when trying to make the context current. By @Imberflur in [#5087](https://github.com/gfx-rs/wgpu/pull/5087).
 
+#### Tests
+
+- Fix intermittent crashes on Linux in the `multithreaded_compute` test. By @jimblandy in [#5129](https://github.com/gfx-rs/wgpu/pull/5129).
+
 ## v0.19.0 (2024-01-17)
 
 This release includes:

examples/src/hello_compute/tests.rs

@@ -57,9 +57,7 @@ static MULTITHREADED_COMPUTE: GpuTestConfiguration = GpuTestConfiguration::new()
         TestParameters::default()
             .downlevel_flags(wgpu::DownlevelFlags::COMPUTE_SHADERS)
             .limits(wgpu::Limits::downlevel_defaults())
-            .skip(FailureCase::adapter("V3D"))
-            // Segfaults on linux CI only https://github.com/gfx-rs/wgpu/issues/4285
-            .skip(FailureCase::backend_adapter(wgpu::Backends::GL, "llvmpipe")),
+            .skip(FailureCase::adapter("V3D")),
     )
     .run_sync(|ctx| {
         use std::{sync::mpsc, sync::Arc, thread, time::Duration};
@@ -69,25 +67,31 @@ static MULTITHREADED_COMPUTE: GpuTestConfiguration = GpuTestConfiguration::new()
         let thread_count = 8;
 
         let (tx, rx) = mpsc::channel();
-        for _ in 0..thread_count {
-            let tx = tx.clone();
-            let ctx = Arc::clone(&ctx);
-            thread::spawn(move || {
-                let input = &[100, 100, 100];
-                pollster::block_on(assert_execute_gpu(
-                    &ctx.device,
-                    &ctx.queue,
-                    input,
-                    &[25, 25, 25],
-                ));
-                tx.send(true).unwrap();
-            });
-        }
+        let workers: Vec<_> = (0..thread_count)
+            .map(move |_| {
+                let tx = tx.clone();
+                let ctx = Arc::clone(&ctx);
+                thread::spawn(move || {
+                    let input = &[100, 100, 100];
+                    pollster::block_on(assert_execute_gpu(
+                        &ctx.device,
+                        &ctx.queue,
+                        input,
+                        &[25, 25, 25],
+                    ));
+                    tx.send(true).unwrap();
+                })
+            })
+            .collect();
 
         for _ in 0..thread_count {
             rx.recv_timeout(Duration::from_secs(10))
                 .expect("A thread never completed.");
         }
+
+        for worker in workers {
+            worker.join().unwrap();
+        }
     });
 
 async fn assert_execute_gpu(