Blender now freezes when long (loop-like) geometry nodes chains are evaluated #93845

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Tom Benedett · 2021-12-08T02:12:09+01:00

Tom Benedett commented

2021-12-08 02:12:09 +01:00

System Information
Operating system: Windows 10
Graphics card: GTX 1080ti

Blender Version
Broken: Blender 3.1, aa440923c8, 2021-11-09 and Blender 3.00 release, f1cca30557, 2021-12-07
Worked: Blender 3.00, 231d66d8ba, master, 2021-10-23

Short description of error
Long chains of math nodes in geometry nodes (specifically discovered in Newton's method numerical solves) that ran speedily in Blender versions up through at least mid-October now require compute time that feels exponential(!) with the number of iterations.

Exact steps for others to reproduce the error
Probably best to try the attached .blend rather than attempt to implement a Newton's method problem yourself.
In the file are four versions of the same geometry nodes parametric-equation solver, differing only in the number of Newton's method iterations. All four of them currently have their "Geometry Nodes" modifiers disabled in the viewport; enable them, one-at-a-time, in ascending order of iteration count (given in the objects' names and their respective nodetree names) and take note of the time it takes to evaluate them.

On my system, with the Oct. 23rd version, the 32-iteration case takes no more than two seconds to evaluate, and all the others are at least as fast.
With the later versions, the 3-iteration case takes less than a second, the 4-iteration case takes about four seconds, and the 8-iteration case freezes blender for at least five minutes (and the 32 iteration case is even worse.)
Parametric Heart - Newton's Method - 3.00 - 2021-12-07.blend

**System Information** Operating system: Windows 10 Graphics card: GTX 1080ti **Blender Version** Broken: Blender 3.1, aa440923c8a3, 2021-11-09 and Blender 3.00 release, f1cca3055776, 2021-12-07 Worked: Blender 3.00, 231d66d8ba35, master, 2021-10-23 **Short description of error** Long chains of math nodes in geometry nodes (specifically discovered in Newton's method numerical solves) that ran speedily in Blender versions up through at least mid-October now require compute time that feels exponential(!) with the number of iterations. **Exact steps for others to reproduce the error** Probably best to try the attached .blend rather than attempt to implement a Newton's method problem yourself. In the file are four versions of the same geometry nodes parametric-equation solver, differing only in the number of Newton's method iterations. All four of them currently have their "Geometry Nodes" modifiers disabled in the viewport; enable them, one-at-a-time, in ascending order of iteration count (given in the objects' names and their respective nodetree names) and take note of the time it takes to evaluate them. On my system, with the Oct. 23rd version, the 32-iteration case takes no more than two seconds to evaluate, and all the others are at least as fast. With the later versions, the 3-iteration case takes less than a second, the 4-iteration case takes about four seconds, and the 8-iteration case freezes blender for at least five minutes (and the 32 iteration case is even worse.) [Parametric Heart - Newton's Method - 3.00 - 2021-12-07.blend](https://archive.blender.org/developer/F12706970/Parametric_Heart_-_Newton_s_Method_-_3.00_-_2021-12-07.blend)

Tom Benedett commented

2021-12-08 02:12:09 +01:00

Added subscriber: @moak

Pratik Borhade commented

2021-12-08 10:22:15 +01:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-12-08 10:42:28 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Hans Goudey commented

2021-12-14 00:55:02 +01:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2021-12-14 00:55:02 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Hans Goudey closed this issue

2021-12-14 00:55:02 +01:00

Hans Goudey self-assigned this 2021-12-14 00:55:02 +01:00

Hans Goudey commented

2021-12-14 00:55:02 +01:00

Could you check the latest build? Jacques has done some great performance improvements lately, that will help this case, particularly 7b88a4a3ba.

On my Ryzen 3700x, the whole node setup executed in about 350ms.

I'm going to close this as resolved, since I'm fairly certain it should be solved, but if it isn't we can reopen this report. Thanks!

Could you check the latest build? Jacques has done some great performance improvements lately, that will help this case, particularly 7b88a4a3ba. On my Ryzen 3700x, the whole node setup executed in about 350ms. I'm going to close this as resolved, since I'm fairly certain it should be solved, but if it isn't we can reopen this report. Thanks!

Tom Benedett commented

2021-12-14 04:38:52 +01:00

Yes, that solves it! It indeed runs speedily as before, even on a significantly less powerful machine than I was testing on before.

Excellent; thank you very much!

Yes, that solves it! It indeed runs speedily as before, even on a significantly less powerful machine than I was testing on before. Excellent; thank you very much!

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Blender now freezes when long (loop-like) geometry nodes chains are evaluated #93845