Maya GPU rendering - "Clearing geometry" quite slow...

[virgil_tanasa]

Good morning,
I've started rendering some of my animations with V-ray and I chose to use the GPU renderer, which seems fast and perfect for what I need at the moment. My GPU is a 3070 RTX. IPR renders and test renders look great and they're very quick to generate, so all is well there.
When I try to do a render, of the whole animation sequence, the render sort of stops at "Clearing geometry" and stays there for about as long as it takes to actually render the frame. Wondering what that message means and if there's anything I can do to speed that up or maybe try rendering the shot, or setting it up another way which avoids it. It feels like the actual render is so quick and sort of wish there would be something I could do to make the "clearing geometry" speed up a bit.
I have tried importing my references in the shot, ticking/unticking some options in the Rendering Overrides, but it made no difference at all. It seems that there isn't much information around about this "Clearing geometry" message, or maybe I've not checked the right places.
Any advice would be very helpful, many thanks in advance.

Best regards,
Virgil

[Muhammed_Hamed]

virgil_tanasa Hi and welcome to the forums!

Clearing Geometry after a frame is rendered, is V-Ray GPU removing some scene data from the GPU memory. This shouldn't take a long time, could it be that you are very close to the memory ceiling on your RTX 3070?
Do you get any warnings in the log?
If you monitor your VRAM usage with GPUZ or AfterBurner, what is the peak GPU memory usage? Here is our guide on optimizing GPU memory usage
Or if possible to send me your scene at muhammed.hamed@chaos.com, I will investigate why clearing Geometry takes this long

Best,
Muhammed

[oglu]

Does it ever finish? Or is there a possibility that its freezing Maya forever?
Im waiting now for 30 minutes.

[oglu]

It might be something different. Cause im not rendering with GPU.
Maybe there is something goin on with the network. And saving my file does take that long. Its 8k.

[SonyBoy]

I'm experiencing this as well, software rendering either progressive or bucket. The image is complete, so it's hard to understand why it would take Vray more than a few milliseconds to dump data, or whatever it's doing in the background. A frustrating time sink. Maya 2023 and Vray 6.20.02.

[Frebban]

Same here. In my current case, 5+ mins (depending on image resolution).
I'm not sure it's the "Clearing geometry" that's time consuming, it's just the last log output.
Log claims: Total time clearing exporter memory 0h 0m 0.2s (0.2 s) ) but the time until the VFB releases (and maya is touchable) is way exceeding that time.

VFB release time in my tests
Image res. 1500x1024: ~20 s
Image res. 6000x4096: ~5 minutes
Using Vray-GPU, Maya 2024.1
V-Ray 6 for Maya, update 2.2, (v6.20.02 from May 28 2024)

EDIT:
Think it is the write to file that is time consuming.
Last line in log while waiting is: [16:17:38.269] Moving hair segments: 0

Next in log when done is: [16:22:30.659] Successfully written image file "E:\Repo\repographics\trunk\3D\renderResults\t mp\a _RenderCamera_UI\test.png"
I'm using light mix so several files are written. Off course: I'm guessing here.

[SonyBoy]

It's actually making this version of Maya and Vray completely unusable. Either there are long waits for "Clearing geometry" to complete, or more often than not it is simply hanging indefinitely, necessitating killing Maya. I'll be rolling back to more stable versions of both apps.

[oglu]

@Frebban could you try to save an .exr instead of a .png?
and second test would be to store on a local hard drive.

[Frebban]

Ok, here is my results for a image with resolution 6000x4096 at very low settings:
Vray-gpu render time before file writing: ~2m40s

Time to release the render (VBF) and get focus back to Maya:
Lightmix ON (40 lights) | png | external disk: ~4 min
Lightmix ON (40 lights) | exr | external disk: ~3 min
Lightmix ON (40 lights) | exr | local disk: ~2m50s min
Lightmix OFF(40 lights) | exr | external disk: 14 sek

Tested to render half resolution 3000x2048 to confirm my suspicion about the file writing:
Lightmix ON (40 lights) | png | external disk: ~1 min (a 1/4 as suspected for half resolution)

File writing for big files takes time, no surprise there.
Can the file writing procedure be made faster? If the file writing could be done in background (if possible) and let the user get focus back to Maya the user experience would be a lot better.
Inform the user that it is the file writing (not Clearing geometry) that takes time.

What I learnt from this is:
Not to use PNG as file format when render big files (normally I don't do that) (exr ~30% faster in this case)
Not use LightMix at all times when render big files.
"Clearing geometry" is actually, "Be really patient, I'm writing files to disk here"

[Frebban]

Tip: If you don't wanna wait when testrendering uncheck "Render Settings|Common|Image File Output|Don't Save Image". Then the waiting is over. Manually saving file to disk (when needed) is a low price to avoid the waiting.
From 4 minutes to 5 seconds in my test case

[oglu]

I get the exact same behavior here. Thanks for testing.
And saving manually is what we do here for years.

[Frebban]

Thanks for pushing me to do the test and confirm the suspicion. Gonna save so much time.

[oglu]

"Inform the user that it is the file writing (not Clearing geometry) that takes time."

Thats a good point.

[SonyBoy]

I can't say that this is a fix, since I'm still experiencing a complete freeze after rendering into VFB. Outputting multichannel EXRs, not using light mix. "Clearing geometry" simply never finishes, task manager shows very low Maya activity, indicating a total crash caused by this function of Vray. This seems to occur when rendering a single frame into VFB, or if an animation it will happen on the last frame too.

[jimjimanyjimjim]

Same as SonyBoy. I rarely post here but this problem is driving me absolutely insane. I have to remember to press Esc just before a render finishes in VFB or another 30mins' waiting ensues.
I'm not on a slow machine. Threadripper 3990x 256GB, RTX3090, super fast 4TB SSDs directly on the motherboard. Maya 2023, Vray 6.20.24.
This is a recent problem I've noticed in the past couple months. Large renders are a disaster (just doing a 16kspherical right now, 2hours to render and now going on 2 hours "clearing geometry" (writing files). It always eventually finishes but also happens on far smaller renders, 2ksquare I've waited a good 30mins before I can use my machine again. Small scene, nothing complex, no displacements. Do NOT even attempt to tick that LightMix pass.
I'm in the middle of a high pressure 18hr/day project and can't take the time and risk to start rolling back and running tests. It's not scene specific. I've dug out old projects that used to finish in a flash and now waiting forever. Any update on this would be extremely appreciated. This is the only mention I've found anywhere online.