sleepy renders?

Started by Polyglyphs, August 17, 2017, 09:08:07 am

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Polyglyphs

How's that for a subject?  Not sure what else to call it, but I'm having a problem with Tg4.1 pausing or stalling during renders... it's as if my PC (tried it on both of them- same thing) goes into a  screen saver mode, power save mode, etc... and my render just sits there incomplete until I wiggle the mouse or click on the screen then it continues.   It's not "pausing" the render, or crashing... it's just hanging until the PC is bumped into waking up.  This is happening on both of my PCs, and I've check the power management, screen savers, time-outs, etc... and have turned all that off, and it's still doing it.

Anyone have any ideas?   Thanks!

P.

Oshyan

Very strange. We certainly haven't seen this in our own tests. Is anyone else experiencing this? Does it only happen during long renders? How long does it typically take to happen, if you know, or is it random? Is it only after the screen goes blank (screen sleep)?

- Oshyan

Asterlil

I'm bumping this rather than starting a new topic because Polyglyphs described the problem so well.

When I discover that the render is hanging, I try pausing it, at which the screen suddenly displays more of the render, as if it were doing the job but not deigning to show me. Then I hit resume, and listen for the CPU fan to know whether it's continuing or not, because the panel no longer shows me the elapsing time. Sometimes it takes a number of "prods" to complete a render.

When it shows "Preparing to render..." but doesn't actually start, I close the program and restart, and that usually helps. I was experiencing just such an endless "Preparing" when I opened this forum, searched for history on the problem, and started this post. I was writing this paragraph when the CPU fan suddenly whirred to life, and lo, now I have a completed render.

Sometimes the RTP button does this, too. The preview prepares forever, or simply doesn't happen; it might say "finished", but the preview is still showing box bounds, not objects. My scene is in its early stages, with no vegetation, no populators, just water, terrain, shaders, and a handful of objects.

Does Terragen avail itself of the GPU memory or what I think you call CUDA? The software for my NVidia board (GTX960M, 2GB of RAM) lets me direct certain apps to use it rather than the integrated Intel graphics, and I did so with Terragen, but I can't tell whether Terragen is using it.

digitalguru

Don't know if this could be the cause of your problem but are high temps throttling your CPU? Or ram paging to disk?

Asterlil

I've watched the task manager during a Terragen render to see if I could figure out what was going on -- screen is appended. My laptop has dual fans, so if I hear the one fan go above a certain pitch, I would turn on the other. Perhaps I should have it on as part of normal practise? But my machine rarely heats up because of the way I use it; the underside is exposed to the air conditioner/ventilator not seven feet from my bed [I'm a paraplegic in a nursing facility]. Second attachment illustrates this.

digitalguru

Looks like your ram is ok if it's only using 64%

QuoteBut my machine rarely heats up because of the way I use it


Terragen will use all of CPU / threads if you let it - you could check if that's a problem by going into the Advanced tab of the render node and setting Maximum Threads to say, half of the threads you have available - then you'll know if Terragen is pushing the CPU too hard. if it is you might want to turn that second fan on  - there should be some kind of program that controls the fan speed according to the CPU temp.

Though seeing it's running on a laptop and depending on the manufacturer they often have a proprietary program in addition to Windows that controls how the machine goes to sleep, maybe that's overriding some setting somewhere?

Oshyan

Have you checked memory usage *when this apparent freeze happens*? My first guess would definitely be paging to virtual memory on disk, because this can be very slow. How much RAM is in your laptop?

- Oshyan

archonforest

I had a similar experience with Blender recently. I still have to investigate what happened.

Some tips that might help when rendering:
-make sure the screensaver is off,
-automatic updates are all off,
-all power management items set to "never" meaning windows will never turn off/sleep the screen, hdd and the pc itself,
-virus scanner is not scanning in the background
-fans control is on automatic mode. (If you manually turn off a fan that might restrict the speed of the cpu. Modern CPUs has a thermal switch? that will not let the cpu overheat. And this means the CPU most probably will drop the speed.)
Dell T5500 with Dual Hexa Xeon CPU 3Ghz, 32Gb ram
Amiga 1200 8Mb ram, 8Gb ssd

Asterlil

@Oshyan, my laptop, an msi QE62 2QD Apache Pro, has 16 GB of RAM.

@archonforest, I can safely check off all the items on that list except for my virus software, which I dare not turn off because I'm on a public wifi system whose password hasn't been changed in six years. Six years!

Asterlil

Ah, caught a live one! The render has hung at 1:34. What you don't see on this screengrab is an intermittent message that says GPU 1 - 3D in the GPU Engine column. It's not in red or blinking, just going on and back off with no apparent regulaity.

digitalguru

QuoteWhat you don't see on this screengrab is an intermittent message that says GPU 1 - 3D in the GPU Engine column.


That's normal - if you had multiple GPUs in your computer, it would tell you which one a program was using - for a laptop it would just show if a program was using the GPU resources.

archonforest

Strange. I did some tests like starting a render and lock the windows or manually start the screensaver while rendering but it did not hang at all...
It is a random phenomena or it happens every time you render?
Dell T5500 with Dual Hexa Xeon CPU 3Ghz, 32Gb ram
Amiga 1200 8Mb ram, 8Gb ssd

Asterlil

I actually do have two GPUs in this laptop, the integrated Intel chip and the NVidia board, and there's an app for me to tell the system which programs should use the NVidia graphics. But your explanation has helped me to understand what's going on, since Chrome occasionally flashes a message for GPU 0, which must be the Intel.

The phenomenon of hanging renders is completely intermittent. I hesitate to use the word "random" because there's bound to be an underlying cause, and the TG team just need more evidence. I'm using the Frontier build, by the way.

Oshyan

Hmm, so not a memory issue. Strange indeed. At what stage of the render did this happen? Was it just finishing, or still in the middle?

- Oshyan

Asterlil

Sometimes the message is "Preparing to render..." And nothing happens for a long time, if ever. Otherwise, the cessation could happen anywhere during the render. Right now my test renders are only a few minutes long, and the hang I logged upthread was about a minute and a half into the job.The longest render I've done so far was a bit over 90 minutes, and it went from start to finish without incident.