Hi Buddhi,
Thank you once again for another version of my favourite fractal renderer.
I just thought I'd let you know that I think I'm getting close to understanding my crash problems, and all evidence points to it not being Mandelbulber's fault at all.
I've noticed previously, that the 'random crashes' I was getting in OpenCL mode seemed to happen most often when a ray was going at a very narrow angle to a surface (or in other words, had a lot more steps to march along the ray), which in turn increased the time it took to calculate that ray.
It seemed quite counter-intuitive, but I've found in versions 1.19 and 1.20, if I reduce the GPU RAM usage to something really small, say 16MB, then it was much more likely to render the problem frames without crashing, as it seemed to be rendering in smaller chunks.
Anyway, I was reading around the forum, and it appears that Fragmentarium has some similar issues, and this explanation from Syntopia seems to be entirely consistent with the problem:
The GPU is completely locked until a frame render completes in Fragmentarium. (Which is why Windows just kills the display driver if a GPU operation takes too long - it cannot show a dialog asking if you want to stop the operation).
Theoretically, the new WDDM 1.2 driver model in Windows 8 supports GPU Pre-emption (multitasking as we know it from desktop OS'es), but I don't know if the Nvidia and AMD drivers implement this yet - I don't think so.
The only way to keep the OS responsive is by rendering smaller tiles.
(I'm sure there was another post that went into more detail, where he said that you could adjust the time-out in the control panel, but that it was a bad idea if you didn't know exactly what you were doing, but I can't seem to find it now).
So it looks like we're just going to have to live with it until Nvidia and AMD start writing drivers that can take this into account.
This is actually fine for me. I've mentioned elsewhere that I've been using a macro recorder to just restart the program if it crashes, and it doesn't happen that much anyway. It seems a small price to pay, but it's good to get to the root of the problem.