Vray RT running only on one core after a while of rendering.

[Fridayvfx]

Hello,

I'm experiencing a weird problem right now with Vray RT. While rendering a large still of an architectural scene with DR
where my workstation and 2 slaves are rendering the image. Noise threshold is set to 0.01 and the GI Engine is set to brute force for primaries as well as for secondaries.
After I start Rendering, all cores on my local machine get utilized as well as on the DR machines.
So far so good. After a While (1-2 hours) suddenly both DR slaves disconnect simultaneously and vray keeps utilizing only one core on my local machine.

This is what the log looks like:
http://fridayvfx.com/clipupload/201611234per7DoO.png

After the disconnect of both DR machines, the windows Resource manager states that Vray only utilizes about 13% of my CPU which means one core is maxed out and the other ones are doing nothing.
Network and disk utilization is minimal.
Note that the noise threshold of 0.010 is not reached yet and all denoiser calculations are done for this step. Until now it has not finished...
I've restarted the rendering now 2 times and it does the same thing all over.
Any Idea what can cause this?

Thanks
-Robert

Edit:
By the way: I'm currently using 3.40.03 and max 2016.

I'm going to try to turn "In-Process RT engine" off. It helped me with some issues in the past. I'll let you know if it worked.

[yavor.rubenov]

Hello,

The main problem here is the restarting of the DR machines. Unfortunately the progressive sampler (and RT as it uses the progressive) doesn't handle DR machine failures yet. So when the machines fail - the main machine will keep waiting for them forever and loading the CPU a little bit.

Can you check the V-Ray log on the DR machines - maybe there will be some info why they fail? Other than that - if you could share a part of the scene with our support guys - they can try to reproduce the problem here and check what is going on.

Best regards,
Yavor

[Fridayvfx]

Hello Yavor, sorry for coming back to you so late. Unfortunately I cannot give out the scene since I have strict client orders.
But I think found out what it's related to. It's somehow related to the Denoiser, because the Problem always happens when the denoiser starts it's work the first time while the overall rendering is still refining.
Setting the "progressive update frequency" to a very low value will cause the error to happen later, higher values will cause it to happen earlier.

What works:
Setting the denoiser to "Only generate render elements".

I hope it helps.

-Robert

[yavor.rubenov]

Hello Robert,

Hmm could you try the same scenario with the DR machines but with a simple test scene - if the same thing happens then probably there is some general problem with the denoiser and the DR machines.
Also could you try turning OFF the hardware acceleration of the denoiser - maybe there is some issue with the drivers or video cards on the DR machines that causes crashes.

Best regards,
Yavor