WebGPU error catching when rendering on worker

[wenhan chong]

Hi All,

I am trying to use WebGPU uncapturederror listener to detect unexpected errors that happen during render time. I notice that errors are suppressed and not captured when I am rendering to an offscreen canvas on a worker. I tested this by forcing a simple GPUValidationError in the shaders. On an app that renders directly on the main thread, I am able to catch the error. However, on an app that renders to an offscreen canvas on a worker thread before transferring to main, the error is not captured. There is also no console output indicating any errors without the use of the uncapturederror listener. The canvas simply doesn't render. Is this a known issue and is there a workaround?

Thanks,
Wen Han

[Brandon Jones]

Hi Wenhan!

I [wrote a quick test](https://codepen.io/toji/pen/ZEmVypz) to try this out and I'm able to see the uncapturederror events in the worker and forward them on to the main thread for logging.

Is there a reduced version of the code that's producing the issue that you could share? Because otherwise it looks like it's working in at least this trivial case.

--Brandon 

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[wenhan chong]

Hi Brandon,

Thanks for looking at this. I compared you sample code against the code in my app and saw that the render loop on my worker thread was causing the issue. It seems that having a render loop on the worker prevents control from returning to the ui thread, thus suppressing any errors thrown by webgpu device. I was able to use the uncapturederror event listener after removing the loop.

Thanks,
Wen Han

[Brandon Jones]

Glad that you were able to figure it out! And yeah, that can be a non-obvious requirement of operating in a worker. I'll see if there's any sensible places for us to surface that to the rest of the community.

--Brandon