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Just cached 1800 frames of a simulation nodes sim. It chugged through them fine (each .blob file is max about 30Mb) but as soon as it had finished the frame range, it crashed. Opening the file makes Blender instantly exit, -pof-. If I delete or move the .blob files, I can open the .blend file fine.

Is there a limit to how much of a cache Blender can cope with? I previously managed to cache the sim fine with the particle life set to a lower value, so there were fewer particles in total (although the .blob files were nearly the same size - max 28Mb).

I've tried this on 4.0.2 and 4.1. System is 128GB RAM, RTX 4090, Ryzen Threadripper 3960X 24-Core cpu.

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  • $\begingroup$ Probably this is the answer but not a positive one blender.stackexchange.com/questions/102149/… $\endgroup$
    – Emir
    Commented Apr 9 at 18:52
  • $\begingroup$ Thanks. Is this a CPU issue though? It averages about 1-2 seconds per frame it's simulating, and it only crashes when trying to retrieve the baked data from the cache. Plenty of free space on the cache ssd too $\endgroup$
    – Nickh129
    Commented Apr 10 at 9:15
  • $\begingroup$ So fwiw I've done some more tests. I went back to an earlier version of this file, which was set up to render in Cycles, and uses Set Point Radius to render the points as spheres, rather than Instance on Points as I've done in the above Eevee setup. The original file has about 1.9m points, and the cached .blobs are ~160Mb per frame. This doesn't crash, and displays pretty much in realtime in the viewport. The Eevee version, instancing spheres on a point cloud of ~160k points, won't even load the cache without crashing Blender. How can I render out points directly in Eevee? $\endgroup$
    – Nickh129
    Commented Apr 10 at 13:42
  • $\begingroup$ I should mention that overall I'd rather use Eevee to render a final version as it's obviously much faster, and I have ~5500 frames to output $\endgroup$
    – Nickh129
    Commented Apr 10 at 13:47

1 Answer 1

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FWIW: This was a RAM issue. I upgraded to 256GB and it chugged through fine. It seems simulation nodes are not very memory efficient in Blender yet, as the amount of RAM used scaled proportionally with the overall size of the cache, rather than Blender just keeping the most recent framestate in RAM.

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