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aero with big sims / resume simulation / set-initial-state

14 REPLIES 14
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Message 1 of 15
doppelgaenger_digital
417 Views, 14 Replies

aero with big sims / resume simulation / set-initial-state

Hey there!

 

I wanted to expand a simulation I did a while ago with the set initial state compound. 

I tested this setup and it works for my .vdbs when they are small. If they get larger, the process seems to get stuck on 2 threads.

 

A while ago I reported bad performance and not being able to resume simulations when I hit the ESC key or manually paused and waited the frame to be finished. I am also not able to just load and preview large VDBs.

I think @PhilRadford experienced something like this too. Maybe there is already a solution to this, I didn't notice?

I am really waiting for a fix for this problem. Bifrost becomes unusable for simulations this way.

 

Even with paused viewport the simulation just hangs on 2 out of 64 threads and I can not quit Maya at all, except by task-manager.

 

 

 

14 REPLIES 14
Message 2 of 15

Hi,

 

Thanks for reporting these issues.

Are you able to share a vdb file that causes a hang when previewed such that we can repro on our side?

Perhaps you already noticed, but the default settings for "Resumable after Esc. Termination" in the Bifrost Graph Editor's Options menu changed. It is now off by default. If that doesn't solve the issue with not being able to resume simulations, please send us repro steps.

I was able to repro the issue with the computation being stuck with on a low number of threads after ESC. I will log this issue and bring it to the attention of QA.

 

Cheers,

Michael



Michael Nielsen

Principal Engineer
Message 3 of 15

Hi Michael!

I am aware that the Resumable option is off by default. I tried all options with no success.

Here is one of the files. 

 

https://www.dropbox.com/t/1CN8TnHl6u3e5s2p

 

 

Message 4 of 15

Thanks for sharing the VDB file.

Are you able to preview the VDB file using a volume scope like shown in the attached image or does the issue only arise when displaying the volume directly in the viewport?

Cheers,

Michael

michaelnielsen_0-1649846131243.png

 



Michael Nielsen

Principal Engineer
Message 5 of 15

QA verified that loading and previewing the VDB takes approx. 20-30 secs. 

Perhaps it's a graphics card issue you're experiencing. What are your machine specs?

Cheers,

Michael

michaelnielsen_0-1649857740033.png

 



Michael Nielsen

Principal Engineer
Message 6 of 15

I tried it with volume scope, but Maya just locks up. 

 

My specs are: 

Threadripper 3970x

128 GB Ram

GTX 1080 8GB

Win 10

Message 7 of 15

Thanks.

Since we're not able to repro on our side, please attach the scene file with the volume scope you used and let us know which version of Bifrost and Maya you're using.

Cheers,

Michael



Michael Nielsen

Principal Engineer
Message 8 of 15

Hi Michael!

 

I've found the error now. The volume loads fine, when I load it from my local drive. But I have the cache files on my mapped network storage. The speed it loads is totally fine. About 800-1000MB/s. But then it gets stuck.

 

When loaded from local disk, Maya CPU usage jumps to 30-50% and it loads in ~15sec.

 

Can you reproduce this?

 

I'm using Maya 2023 and Bifrost 2.4.

Message 9 of 15

Hi again,
FYI, we can reproduce the issue when loading a vdb on a slow network drive.
We're also looking into the ESC termination issue now.
Cheers,
Michael



Michael Nielsen

Principal Engineer
Message 10 of 15

I know my network speed with small random reads is slow compared to SSD, but large sequential reads are faster than single SSD speeds. 

My vdbs are large and read in quickly.

 

I am looking forward to a fix for this issue.

Message 11 of 15

Thanks for reporting these issues.

Do you by any chance know if loading large vdbs from your network drive causes issues in other packages besides maya/bifrost? And have you seen similar issues with e.g. bob files?

Cheers,

Michael



Michael Nielsen

Principal Engineer
Message 12 of 15

hi michael!

 

I never have issues on my network except with large vdbs and saving USD files (but this is another topic I already reported)

 

I just tested with the same VDB converted to .bob and read in from my network and it works just fine. Reads in at expected speeds and no hang ups.

Message 13 of 15

Hello again.

Thanks for this info.

QA was able to load your vdb file into Bifrost over a slow network connection, it just took a very long time. Same behavior in another package. So our tests there are not fully conclusive yet. 

 

Regarding the ESC issue, as I mentioned earlier I was able to repro. But the issue on my side turned out to be related to the fact that instead of outputting the aero volume from the graph (to rule out issues with volume draw) I was outputting an array which turned out to have a large number of entries which in turn created a problem/hang because it apparently creates a plug for each point in the array. If this is unrelated to your problems with ESC termination, please give us a bit more info and ideally repro steps and a scene file.

 

Cheers,

Michael



Michael Nielsen

Principal Engineer
Message 14 of 15

hi michael!

 

I have no problems with reading and previewing my vdbs in a vray volume grid for example. Reads in quickly from my network, draws and renders fine.

 

What you describe sounds like the VDB files contains more arrays that it should have? 

I just had a file_cache node and voxel_fog_density, voxel_temperature, voxel_velocity exported.

The files I provided are the exact same setup I have. Nothing fancy there. I just setup a basic combustion sim, hooked up set_initial_state to addidtional aero solver settings.

Message 15 of 15

Thanks for the description of the initial state issue!

Cheers,

Michael



Michael Nielsen

Principal Engineer

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