Arnold render slows down over time?

[matt_gold_99]

Hey all

I am rendering a very very long and intensive sequence.  around 2300 frames.  Very large textures and very high-poly photogrammetry.  

I am rendering in 3DS Max - Arnold.  I am rendering CPU, not GPU.  That's important, as I can understand GPU having issues with such large texture maps.

I find that over the course of a few hundred frames, maybe 3 or 4 hundred, my rendering times slowly drop from around 30 seconds per frame, to around 90 seconds per frame.  This can easily be solved by stopping the render, quitting Max, reloading the scene, and resuming the render on the latest frame rendered.

Can anyone think of a reason or a solution for this, or has anyone had this experience?

[thiago.ize]

What version of Arnold are you using? Can you provide a complete info level log so we can see what's going on?

[matt_gold_99]

Sure...I am using 3ds max 2021,

MAXtoA 4.3.4.12

Arnold 6.2.1.1

If you tell me how to create a log, I can create one and attach it.

Being subscription based, I also have Max 2023 installed with the latest Arnold.  I hesitate to use it as I have found that when you find a nice combination of software/versions that is stable without crashing, best to stick with it.  That said, perhaps I'll try rendering it in max 2023 with the latest arnold....just to see if it works.

[Stephen.Blair]

If you're batch rendering the frames already, why not do it in smaller chunks, like 100 frames at a time?

Log verbosity and other settings are in the Arnold Render Setup, Diagnostics tab.

https://docs.arnoldrenderer.com/display/A5AF3DSUG/Log

[matt_gold_99]

I'm not batch rendering. I want to render all 2300 frames without having to restart max. Shouldn't be an issue. I can actually do it right now, but the frame render times slowly go up, so the whole thing would take me 4 or 5 days instead of 1 o 2 days.

[matt_gold_99]

I am assuming that I need to set the log file to write (info), then try to render overnight, then I'll have a log file to work with, and attach it here?

[thiago.ize]

Before doing an overnight run, render just a few frames and check if the log file looks complete and if so, upload it here so we can confirm it's properly set up and maybe see if we can already spot a possible issue.

Giving the latest Arnold a test when you're encountering a problem is always recommended.

[matt_gold_99]

Here it is.  If anyone has a second, let me know if anything sticks out as a render-time increasing issue.

[thiago.ize]

Looks like the log is missing all the useful information. Did you also enable the logging in the "Preference Settings" as shown in https://docs.arnoldrenderer.com/display/A5AF3DSUG/Log? You need to do it both here and in the arnold diagnostics tab.

[matt_gold_99]

my apologies.  I had done the preferences part, but reloaded the scene and forgot to do it again.  

[thiago.ize]

This log is good. Do this for the full render and hopefully we'll see what's up.

One thing I already noticed: You have the negative AA progressive rendering enabled (starts off with a low res blocky looking render before it refines). That is just wasted computation, so if you aren't looking at the renders, disable that and you will get a speedup.

From what I see in your log, it looks like memory is growing with almost every frame. My guess is that you eventually run out of RAM and that's when things really start to slow down. The log should make that clear.

[matt_gold_99]

Sorry for the delayed response, I was gone for the weekend.  YAY.

So, I rendered a large group of frames last night, switching to Max2023 and thus Arnold 7.1.3.0, and I didn't encounter the increasing frame-time issue.  So the most obvious solution, using updated versions, seems to the the right one.

I also forgot to write the log file.  I might render again tonight (I forgot to turn on my vector blur AOV, and a few other mistakes) so if I do, I'll post it here.  But for now, my problem is solved.

[thiago.ize]

Glad to hear this bug has likely already been fixed 🙂