Cycles renderer stuck on loading render kernel, attempting to cancel rendering causes UI to freeze completely #120800

New Issue

Qurat-ul-Ain-Sebba · 2024-04-19T00:56:58+02:00

2024-04-19 00:56:58 +02:00

System Information
Operating system: Linux-6.8.5-arch1-1-x86_64-with-glibc2.39 64 Bits, WAYLAND UI
Graphics card: Mesa Intel(R) Arc(tm) A750 Graphics (DG2) Intel 4.6 (Core Profile) Mesa 24.0.5-arch1.1

Blender Version
Broken: version: 4.2.0 Alpha, branch: main, commit date: 2024-04-18 01:19, hash: 9cb3a17352bd
Worked: 4.1 was formerly functional, but is not any longer. Tested with 4.2 Alpha and 3.6 LTS as well.

Short description of error
When attempting to use the Cycles render engine, either in the Viewport or in the actual render, the rendering does not progress past the "loading render kernels" stage. Attempting to stop the rendering in any way results in the UI becoming completely non-responsiv, Blender freezing, and needing to be terminated manually via a killall command or similar. Things which cause the UI freeze include but may not be limited to: changing the shading type from "Rendered" to anything else (Solid, Material Preview, and Wireframe all consistently recreate the issue), changing the render device from GPU to CPU, attempting to quit the program during the render, and turning off GPU rendering under preferences. If rendering by pressing F12, pressing the cancel render button does not cause a UI freeze, but the render never finishes cancelling.

Exact steps for others to reproduce the error

Starting in a new default file, go to Render settings, and change render engine to Cycles.
Under "Device", select GPU Compute.
Change the shading mode to Rendered (press Z to do so).
Attempt to change the shading mode to something else/change render device to CPU/quit the program/disable GPU rendering under preferences by setting the Cycles render device to None.

I have found that these steps are able to consistently recreate this error. Unfortunately, since Blender does not actually crash at any point (needing to be closed forcibly), it is impossible to get a log of crash. Please find attached the output from the terminal when Blender is launched with the flag "--verbose 7".

**System Information** Operating system: Linux-6.8.5-arch1-1-x86_64-with-glibc2.39 64 Bits, WAYLAND UI Graphics card: Mesa Intel(R) Arc(tm) A750 Graphics (DG2) Intel 4.6 (Core Profile) Mesa 24.0.5-arch1.1 **Blender Version** Broken: version: 4.2.0 Alpha, branch: main, commit date: 2024-04-18 01:19, hash: `9cb3a17352bd` Worked: 4.1 was formerly functional, but is not any longer. Tested with 4.2 Alpha and 3.6 LTS as well. **Short description of error** When attempting to use the Cycles render engine, either in the Viewport or in the actual render, the rendering does not progress past the "loading render kernels" stage. Attempting to stop the rendering in any way results in the UI becoming completely non-responsiv, Blender freezing, and needing to be terminated manually via a killall command or similar. Things which cause the UI freeze include but may not be limited to: changing the shading type from "Rendered" to anything else (Solid, Material Preview, and Wireframe all consistently recreate the issue), changing the render device from GPU to CPU, attempting to quit the program during the render, and turning off GPU rendering under preferences. If rendering by pressing F12, pressing the cancel render button does not cause a UI freeze, but the render never finishes cancelling. **Exact steps for others to reproduce the error** 1. Starting in a new default file, go to Render settings, and change render engine to Cycles. 2. Under "Device", select GPU Compute. 3. Change the shading mode to Rendered (press Z to do so). 4. Attempt to change the shading mode to something else/change render device to CPU/quit the program/disable GPU rendering under preferences by setting the Cycles render device to None. I have found that these steps are able to consistently recreate this error. Unfortunately, since Blender does not actually *crash* at any point (needing to be closed forcibly), it is impossible to get a log of crash. Please find attached the output from the terminal when Blender is launched with the flag "--verbose 7".

Blender terminal output.txt

3.9 KiB

Qurat-ul-Ain-Sebba added the

labels 2024-04-19 00:56:58 +02:00

Pratik Borhade commented

2024-04-19 04:27:54 +02:00

Hi, thanks for the report. Render kernel loading is mostly one time process. It does take significant time to load. Forcefully terminating will indeed cause the freeze (not a bug). I would suggest to wait for kernels to load. If "loading" taking more time than usual then it's worth looking at why it's taking that long.

Worked: 4.1 was formerly functional,

Have you recently made any changes on GPU side?

Hi, thanks for the report. Render kernel loading is mostly one time process. It does take significant time to load. Forcefully terminating will indeed cause the freeze (not a bug). I would suggest to wait for kernels to load. If "loading" taking more time than usual then it's worth looking at why it's taking that long. > Worked: 4.1 was formerly functional, Have you recently made any changes on GPU side?

Pratik Borhade added

Status

Needs Information from User

and removed

Status

Needs Triage

labels 2024-04-19 04:28:05 +02:00

Qurat-ul-Ain-Sebba commented

2024-04-19 16:26:21 +02:00

Thank you for the kind and timely response.

I have made no changes on the GPU side in terms of hardware. There may have been changes to the graphics software stack, but I'm not sure what change may have caused this issue.

I am aware that loading render kernels is a one-time process. However, I have previously loaded render kernels on this version/installation of Blender, and in all prior instances the process took mere seconds. I have also tried waiting around 10-15 minutes for it to load, which did bear fruit in one instance where the render kernels did ultimately load and I was able to render successfully. However, I could not recreate this behavior, and on all subsequent attempts Blender has attempted to reload the render kernels.

Thank you for the kind and timely response. I have made no changes on the GPU side in terms of hardware. There may have been changes to the graphics software stack, but I'm not sure what change may have caused this issue. I am aware that loading render kernels is a one-time process. However, I have previously loaded render kernels on this version/installation of Blender, and in all prior instances the process took mere seconds. I have also tried waiting around 10-15 minutes for it to load, which did bear fruit in one instance where the render kernels did ultimately load and I was able to render successfully. However, I could not recreate this behavior, and on all subsequent attempts Blender has attempted to reload the render kernels.

Pratik Borhade commented

2024-04-23 11:10:05 +02:00

Thanks. BTW, did you observe this in previous blender versions. 3.6 for example?
Long loading time was expected initially: https://devtalk.blender.org/t/cycles-intel-oneapi-device-feedback/24928

Kernels are compiled when rendering for the first time. Currently this can be slow, for example 15 minutes. We are working to bundle compiled kernels with Blender for the final release instead.

Situation might have improved by now

If this is an recent issue observed on 4.1, it could be the recent changes on GPU denoiser side affected the kernel loading time? Does this happen after disabling denoiser?

Thanks. BTW, did you observe this in previous blender versions. 3.6 for example? Long loading time was expected initially: https://devtalk.blender.org/t/cycles-intel-oneapi-device-feedback/24928 ``` Kernels are compiled when rendering for the first time. Currently this can be slow, for example 15 minutes. We are working to bundle compiled kernels with Blender for the final release instead. ``` Situation might have improved by now If this is an recent issue observed on 4.1, it could be the recent changes on GPU denoiser side affected the kernel loading time? Does this happen after disabling denoiser?

Qurat-ul-Ain-Sebba commented

2024-04-24 03:53:20 +02:00

Having tested on 3.6, the issue does in fact persist, thus leading me to believe that the root cause of the issue may lie in some particular interaction between Blender and the graphics drivers. I have also tried waiting for a full hour for the render kernels to load. No luck.

As for GPU denoising, the issue persists regardless of whether denoising is enabled or not.

Having tested on 3.6, the issue does in fact persist, thus leading me to believe that the root cause of the issue may lie in some particular interaction between Blender and the graphics drivers. I have also tried waiting for a full hour for the render kernels to load. No luck. As for GPU denoising, the issue persists regardless of whether denoising is enabled or not.

Alaska commented

2024-04-24 12:05:32 +02:00

I just wanted to add that I can't reproduce the issue.

Based on the fact things worked just fine in Blender 3.6 and some other versions, then at some point it stopped working, I would guess that your level zero/Intel compute runtime updated. And now it's broken (either due to a faulty install) or because the person maintaining that package in your package manager didn't compile properly.

Another possibility is that your Level zero/Intel compute runtime is too old. Apparently there were some issues with them with Linux Kernel 6.8.X, and it was only fixed in the last 5 days.

If you have the time, you could try investigating this.

System Information
Operating system: Linux-6.5.0-28-generic-x86_64-with-glibc2.39 64 Bits, WAYLAND UI
Graphics card: Mesa Intel(R) Arc(tm) A750 Graphics (DG2) Intel 4.6 (Core Profile) Mesa 24.0.5-1ubuntu1
Blender version: 4.1.1, branch: blender-v4.1-release, commit date: 2024-04-15 15:11, hash: e1743a0317bc
Blender version: 4.2.0 Alpha, branch: main, commit date: 2024-04-23 21:08, hash: ce768d43a121

I just wanted to add that I can't reproduce the issue. Based on the fact things worked just fine in Blender 3.6 and some other versions, then at some point it stopped working, I would guess that your level zero/Intel compute runtime updated. And now it's broken (either due to a faulty install) or because the person maintaining that package in your package manager didn't compile properly. Another possibility is that your Level zero/Intel compute runtime is too old. Apparently there were some issues with them with Linux Kernel 6.8.X, and it was only fixed in the last 5 days. If you have the time, you could try investigating this. **System Information** Operating system: Linux-6.5.0-28-generic-x86_64-with-glibc2.39 64 Bits, WAYLAND UI Graphics card: Mesa Intel(R) Arc(tm) A750 Graphics (DG2) Intel 4.6 (Core Profile) Mesa 24.0.5-1ubuntu1 Blender version: 4.1.1, branch: blender-v4.1-release, commit date: 2024-04-15 15:11, hash: `e1743a0317bc` Blender version: 4.2.0 Alpha, branch: main, commit date: 2024-04-23 21:08, hash: `ce768d43a121`

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Cycles renderer stuck on loading render kernel, attempting to cancel rendering causes UI to freeze completely #120800