Create a seperate event for each fence wait. (#8273)

* create an event per fence wait

* Use seperate event for each `wait_for_present_queue_idle` call.

* changelog

CHANGELOG.md

@@ -214,6 +214,7 @@ By @cwfitzgerald in [#8162](https://github.com/gfx-rs/wgpu/pull/8162).
 
 #### DX12
 
+- Create an event per wait to prevent 60 second hangs in certain multithreaded scenarios. By @Vecvec in [#8273](https://github.com/gfx-rs/wgpu/pull/8273).
 - Fixed a bug where access to matrices with 2 rows would not work in some cases. By @andyleiserson in [#7438](https://github.com/gfx-rs/wgpu/pull/7438).
 
 ##### EGL

wgpu-hal/src/dx12/device.rs

@@ -195,10 +195,7 @@ impl super::Device {
         Ok(super::Device {
             raw: raw.clone(),
             present_queue,
-            idler: super::Idler {
-                fence: idle_fence,
-                event: Event::create(false, false)?,
-            },
+            idler: super::Idler { fence: idle_fence },
             features,
             shared: Arc::new(shared),
             rtv_pool: Arc::new(Mutex::new(rtv_pool)),
@@ -256,16 +253,14 @@ impl super::Device {
             return Err(crate::DeviceError::Lost);
         }
 
+        let event = Event::create(false, false)?;
+
         let value = cur_value + 1;
         unsafe { self.present_queue.Signal(&self.idler.fence, value) }
             .into_device_result("Signal")?;
-        let hr = unsafe {
-            self.idler
-                .fence
-                .SetEventOnCompletion(value, self.idler.event.0)
-        };
+        let hr = unsafe { self.idler.fence.SetEventOnCompletion(value, event.0) };
         hr.into_device_result("Set event")?;
-        unsafe { Threading::WaitForSingleObject(self.idler.event.0, Threading::INFINITE) };
+        unsafe { Threading::WaitForSingleObject(event.0, Threading::INFINITE) };
         Ok(())
     }
 
@@ -2252,7 +2247,9 @@ impl crate::Device for super::Device {
             return Ok(true);
         }
 
-        unsafe { fence.raw.SetEventOnCompletion(value, self.idler.event.0) }
+        let event = Event::create(false, false)?;
+
+        unsafe { fence.raw.SetEventOnCompletion(value, event.0) }
             .into_device_result("Set event")?;
 
         let start_time = Instant::now();
@@ -2288,7 +2285,7 @@ impl crate::Device for super::Device {
 
             match unsafe {
                 Threading::WaitForSingleObject(
-                    self.idler.event.0,
+                    event.0,
                     remaining_wait_duration.as_millis().try_into().unwrap(),
                 )
             } {

wgpu-hal/src/dx12/mod.rs

@@ -653,7 +653,6 @@ impl Drop for Event {
 /// Helper structure for waiting for GPU.
 struct Idler {
     fence: Direct3D12::ID3D12Fence,
-    event: Event,
 }
 
 #[derive(Debug, Clone)]