Complex node setup: Longer render times in experimental build vs. stable release #70609

New Issue

Johannes Lampert · 2019-10-07T16:58:57+02:00

Johannes Lampert commented

2019-10-07 16:58:57 +02:00

System Information
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: 2x GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.86

Blender Version
Broken: version: 2.81 (sub 14), branch: master, commit date: 2019-10-06 14:05, hash: 54a9649e26

Short description of error
I've noticed that certain (very complex) shader node setups yield much longer render times on the current experimental build compared with the 2.80 stable release.

To demonstrate this, I've deliberately created a complex test shader with various layers of nested node groups (which perform a bunch of mathematical operations with Math nodes). The final output is just a black cube.

Rendering the exact same file on my machine (specs listed above) with both stable release and experimental build yields following render times:

Average render time with 2.80.75 stable release: 0.48 seconds
Average render time with latest experimental build: 4.30 seconds

Exact steps for others to reproduce the error

Download & open attached .blend file
Render on both stable release & latest experimental build
Compare results

bug_complexnodes_alterdings.blend

**System Information** Operating system: Windows-10-10.0.17763 64 Bits Graphics card: 2x GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.86 **Blender Version** Broken: version: 2.81 (sub 14), branch: master, commit date: 2019-10-06 14:05, hash: `54a9649e26` **Short description of error** I've noticed that certain (very complex) shader node setups yield much longer render times on the current experimental build compared with the 2.80 stable release. To demonstrate this, I've deliberately created a complex test shader with various layers of nested node groups (which perform a bunch of mathematical operations with Math nodes). The final output is just a black cube. Rendering the exact same file on my machine (specs listed above) with both stable release and experimental build yields following render times: Average render time with 2.80.75 stable release: **0.48 seconds** Average render time with latest experimental build: **4.30 seconds** **Exact steps for others to reproduce the error** 1. Download & open attached .blend file 2. Render on both stable release & latest experimental build 3. Compare results [bug_complexnodes_alterdings.blend](https://archive.blender.org/developer/F7794736/bug_complexnodes_alterdings.blend)

Johannes Lampert commented

2019-10-07 16:58:57 +02:00

Added subscriber: @alterdings

Germano Cavalcante commented

2019-10-09 15:08:35 +02:00

Added subscribers: @fclem, @brecht, @mano-wii

Germano Cavalcante commented

2019-10-09 15:08:35 +02:00

Some changes in the node system were made during the releases.
@brecht, do you know if any of them justify this delay?
Cc @fclem

(4 seconds doesn't look like much since it's only on initial load).

Some changes in the node system were made during the releases. @brecht, do you know if any of them justify this delay? Cc @fclem (4 seconds doesn't look like much since it's only on initial load).

Johannes Lampert commented

2019-10-09 16:56:53 +02:00

In #70609#792648, @mano-wii wrote:

(4 seconds doesn't look like much since it's only on initial load).

Thanks for your reply. The 4 second difference applies only to this example of course, I've had this same issue with other, more complex files where the discrepancy in render times was far greater.

> In #70609#792648, @mano-wii wrote: > (4 seconds doesn't look like much since it's only on initial load). Thanks for your reply. The 4 second difference applies only to this example of course, I've had this same issue with other, more complex files where the discrepancy in render times was far greater.

Charlie Jolly commented

2019-10-09 17:58:17 +02:00

Added subscriber: @CharlieJolly

Charlie Jolly commented

2019-10-09 17:58:17 +02:00

Confirmed. Just changing the colour on the material takes ages to update and this is not the case on 2.80.

Clément Foucault commented

2019-10-09 18:24:16 +02:00

The issue is caused by the nodegroup flattening, which does the same thing as you would do if you manually ungrouped every nodegroup.

The problem comes from nodeUniqueName which is checking if the nodetree does not have two node with the same name. And it does that for each node added from ungrouped nodegroups.

As far as I can remember we don't use names to identify nodes in the GPU nodetree evaluation so it might be OK to bypass it. But maybe some utility functions are using names.

@brecht Any input on this?

The issue is caused by the nodegroup flattening, which does the same thing as you would do if you manually ungrouped every nodegroup. The problem comes from nodeUniqueName which is checking if the nodetree does not have two node with the same name. And it does that for each node added from ungrouped nodegroups. As far as I can remember we don't use names to identify nodes in the GPU nodetree evaluation so it might be OK to bypass it. But maybe some utility functions are using names. @brecht Any input on this?

blender-admin commented

2019-10-09 23:45:31 +02:00

This issue was referenced by 8163fda9fb

This issue was referenced by 8163fda9fb8b89ce9a58fcbb6310b2bb9d78da73

Clément Foucault commented

2019-10-09 23:48:46 +02:00

Changed status from 'Open' to: 'Resolved'

Clément Foucault closed this issue

2019-10-09 23:48:46 +02:00

Clément Foucault self-assigned this 2019-10-09 23:48:46 +02:00

Charlie Jolly commented

2019-10-10 10:46:54 +02:00

This is vastly improved with the fix but the material updates (e.g when changing colour) are still slower on the latest builds. On 2.80 it is real time but on latest build there is a small lag.
@alterdings Out of interest what time do you get now?

This is vastly improved with the fix but the material updates (e.g when changing colour) are still slower on the latest builds. On 2.80 it is real time but on latest build there is a small lag. @alterdings Out of interest what time do you get now?

Johannes Lampert commented

2019-10-10 11:19:03 +02:00

In #70609#793080, @CharlieJolly wrote:
@alterdings Out of interest what time do you get now?

Is the fix already implemented in the latest daily build (hash: f61a8a2abd)? If so, I'll download it and try it out.

> In #70609#793080, @CharlieJolly wrote: > @alterdings Out of interest what time do you get now? Is the fix already implemented in the latest daily build (hash: f61a8a2abd07)? If so, I'll download it and try it out.

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Complex node setup: Longer render times in experimental build vs. stable release #70609