问题
We have an app that uses Metal to render. This app works correctly on devices running iOS11. When using the same app on devices running iOS12, we started getting glitches and sometimes hangs in the rendering. We also tried recompiling for iOS12 and are getting the same bad behavior. On the console we are getting the following different messages:
2018-09-22 09:22:29.508576-0500 OurApp [1286:84481] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)
2018-09-22 09:29:55.654426-0500 OurApp [1286:84625] Execution of the command buffer was aborted due to an error during execution. Caused GPU Hang Error (IOAF code 3)
2018-09-22 09:34:37.718054-0500 OurApp [1286:87354] Execution of the command buffer was aborted due to an error during execution. Ignored (for causing prior/excessive GPU errors) (IOAF code 4)
With the first two messages the rendering seems glitchy, where a blank screen is presented and then finally the rendering occurs on screen. With the last message the rendering doesn't actually occur and the message continues being displayed until we move to a different view.
This app uses SceneKit, instantiates a SCNView and uses a default CIContext. It also uses the Physically Based Lighting model, which forces the Metal renderer to be used. The app has a simple SCNNode geometry, a cylinder. Each geometry object of the cylinder gets a normal texture (3 in total). The same diffuse, metalness and roughness values are applied to all the geometry objects of the cylinder.
Has anybody ran into this problem? If so, how did you solve it?
Thanks
UPDATE: The problem seems to be caused when an image is used as the scene's lighting environment:
let scene = SCNScene()
scene.lightingEnvironment.contents = UIImage(named: "ourLightingEnvironmentImage")
When a lighting environment isn't used, the problem goes away. This is starting to look like an Apple bug, we will file one. We are stuck because we need the lighting environment to produce realistic reflections for the models in our app.
回答1:
I was able to solve my issues for the moment by choosing OpenGL ES as render mode:
回答2:
I just received an update to the bug I had filed with Apple:
Apple Developer Relations
We believe this issue is resolved in the latest iOS 12.2 beta. Please test with the latest iOS beta. If you still have issues, please update your bug report with any relevant logs or information that could help us investigate. iOS beta https://developer.apple.com/download/"
回答3:
It's a bug, caused by high resolution environment lightning images.
The solution is to resize these images, 1000x500 is what we are using now. Works perfectly.
回答4:
I seem to be having the exact same problem. Also using ARKit and the default sceneKit Editor, I kept getting the IOAF code 4 error infinitely when the screen freezes up.
I fixed my problem by changing the environment from "Procedural Sky" to "None". Doesn't lag or freeze anymore, but this is hardly the solution as my AR object now has no lighting or environment. I believe there is a fix coming in iOS 12.2 Beta, but have yet to update.
Hope my solution helps others.
来源：https://stackoverflow.com/questions/52460670/ios12-is-causing-an-error-on-metal-command-buffer-execution-render-is-glitchy-o