Ensure renderer-api-driven frame wait is only invoked when a frame is actually drawn #5846
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… actually drawn I noticed very long pauses when loading song select on my windows PC. Tracking this down, the game was getting stuck on the D3D11Swapchain wait handle (https://github.com/ppy/veldrid/blob/d4340776eba0541aa3598856dafccf25633072f2/src/Veldrid/D3D11/D3D11Swapchain.cs#L303) until the full one second timeout. It turns out that the wait handle will not be set unless a frame finishes rendering. The fail case is where the update thread takes over 100ms to prepare a frame, causing `TripleBuffer.GetForRead` to timeout and return `null`, which early exits the draw frame method. This would happen anywhere the game takes slightly too long to render an update frame. I could reproduce: - Entering song select - Opening settings - Opening beatmap listing To confirm / reproduce this issue, remove the 1000ms timeout from `WaitOne` in veldrid and add a single `Thread.Sleep(150)` in any update thread code, and watch the game deadlock indefinitely.
bdach
approved these changes
Jun 17, 2023
|
On Metal, the display link callback is always signalled regardless of whether a frame was drawn, so this doesn't quite have an effect on renderer. Testing confirms that anyways. |
frenzibyte
approved these changes
Jun 17, 2023
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I noticed very long pauses when loading song select on my windows PC. Tracking this down, the game was getting stuck on the D3D11Swapchain wait handle until the full one second timeout.
It turns out that the wait handle will not be set unless a frame finishes rendering. The fail case is where the update thread takes over 100ms to prepare a frame, causing
TripleBuffer.GetForReadto timeout and returnnull, which early exits the draw frame method.This would happen anywhere the game takes slightly too long to render an update frame. I could reproduce:
To confirm / reproduce this issue, remove the 1000ms timeout from
WaitOnein veldrid and add a singleThread.Sleep(150)in any update thread code, and watch the game deadlock indefinitely.For good measure, here's a visual example of this happening: