Rendering freezes Cinema 4D with Version 2023.2.0

[dominik.source]

I updated to the new Cinema 4D 2023.2.0 and every render froze Cinema after a few seconds. I tested it with both C4DtoA 4.6.2 and 4.6.1 – both have the same problem. I'm on a M1 Mac using macOS 12.4. Now I reverted back to 2023.1.3 and everything works fine. Any ideas what causes these problems. For my tests I simply used a sphere with a standard_surface applied and a physical sky. Thanks!

[peter_horvath]

I can not reproduce the hang on my M1 Mac, everything works normally. Does it happen only in the IPR or only when rendered to the Picture Viewer? Or both? What about material previews, are they rendering fine?

[dominik.source]

I only encountered it when rendering to the Picture Viewer, but I didn't really have time to test it extensively. Due to an urgent job I needed to revert back to 2023.1.3. I will install 2023.2 again soon and hopefully I can provide more details then. Just wanted to ask in the meantime ... Thanks!

[dominik.source]

Hi Peter, I did some more tests:

1. I also tried it on an Intel machine (iMac Retina 5K, 27-inch, 2019) with macOS 11.2.3 and the same Versions (C4D 2023.2 and C4DtoA 4.6.2) and had no problems so far. 

2. Then I reinstalled 2023.2 on the M1 Mac, but this time I did not replace the old 2023.1.3 version, instead I installed it in a new directory – but it still hangs when rendering (mostly after around 30 seconds render time, but that varies).

3. I did some more tests with the IPR and had now problems. So for me it only occurs when rendering to the Picture Viewer. (Material previews render ok)

I also attached the crash log – theoretically I can provide more crash logs, but I guess they're the same every time.

Thanks!

[peter_horvath]

I'm still not able to reproduce the hang. I've rendered several frames multiple times without any issues, each taking more than 2 minutes to render. I've also checked with one of our customers using Arnold in Cinema 4D 2023.2 on M1 (macOS 12.6.5) and he had no issues either. Seems like a local problem (maybe with the OS or environment), but I'm lost at this point.

Does this happen with other renderers in Cinema 4D 2023.2 or only Arnold?

Does it make any difference if you reduce the thread count in Arnold Render Settings > System > Threads? Maybe try with a single thread first.

[dominik.source]

Hi Peter, thanks for your reply and for testing it on another machine!

1. Yes, lowering the threads to 1 seem to work. But using more than 1 thread leads to the same issue.

2. I also had the chance to test the same software setup (C4D 2023.2.0 with C4DtoA 4.6.2) on a completely different Apple Silicon machine (MacMini M2 Pro, macOS 13.3) with the same results: It hangs when rendering with more than one thread but works fine when rendering on 1 thread only. (I also attached the crash log from the MacMini here, but I guess that's no help either.) So my initial thought was, that it's a problem with my scene file. But It also happened with other projects.

3. I also tested another scene with the physical renderer and had no problems (I only made 3 simple tests)

In my original post I wrote that it froze every time. Although that was true – after about 30 more test renderings  I can now say that it almost always happens, but not every time. 

Also I think I misinterpreted the 30 seconds when the hang occurs – after some more tests I think it's more accurate to say that it almost always hangs shortly before the rendering is finished, no matter how long that is. But that's more a feeling ...

Do you have any thought about this – especially on why it works with only 1 thread? Thanks!

[peter_horvath]

Could be some sort of thread synchronization issue, but hard to tell. We're checking on multiple machines here, hoping we can repro.

[dominik.source]

Thanks for your help, Peter! I hope so too. If I can test anything else here on my machine, let me know.

I attached one of my test scene files. This is the one that leads to the most crashes here on my machine. It's super simple, it's just a sphere with a physical sky. According to my own tests the problem is not attached to a specific file. But maybe you will check nonetheless?!

[peter_horvath]

Good news, I can reproduce the hang with your scene. Not sure yet what's going on, might be something to do with the resolution, but don't wanna guess blindly. At least I can start investigating now. Thank you, will keep you updated.

[dominik.source]

Awesome! Thanks again!

[peter.fagerberg]

Great that @peter_horvath is able to reproduce it!  Just to let you know that this has happened to me with 4.6.2 (C4D 2023.2.1) as well. The picture viewer stops updating, but the timer continues... However, a version of R25 with C4DTOA 4.6.1, seems to run fine, so unlike @dominik.source I seem to have a fallback. Hope you're able to find out what's wrong. 🙂

PS I also managed to save a scene file where the problem occurred. Let me know if you need it!

Mac Studio Apple M1 Ultra, 64 GB, macOS Ventura 13.3.1.

[peter_horvath]

Hey guys, seems like something has changed in thread management in Cinema 4D 2023.2, which is causing the hang. I contacted Maxon to confirm and meanwhile I implemented a workaround. If you'd like to test it, please contact support(at)arnoldrenderer(dot)com and refer to this post.

[dominik.source]

Sounds great! I would love to test – I will send an email soon. Thanks Peter!

And thanks @peter.fagerberg for confirming the bug!

[peter.fagerberg]

It looks like @peter_horvath nailed it! I've done two long overnight renders of scene files that gave me trouble before, and everything ran smoothly with the updated beta version of CD4TOA (4.6.2.1.wip01 [a5d23296]). Good work!