Very slow performance and "Using fallback". #87468

New Issue

Will · 2021-04-13T18:48:55+02:00

Will commented

2021-04-13 18:48:55 +02:00

System Information
Operating system: Linux
Graphics card: Intel

Blender Version
Broken: 2.92

Short description of error

I have a .blend file where any basic edit like moving an object between collections seems to cause a freeze lasting several seconds to a minute, with the following output in the terminal:

Using fallback
Using fallback
Using fallback
Using fallback
Using fallback
Using fallback
Using fallback
Using fallback
Using fallback
Using fallback

I don't think I can share the file, and the slow nature of the freeze and vagueness of the error report make it an unappealing prospect to try to narrow the bug down with no further information.

However, if someone familiar with the code could say what kind of circumstances this error message gets printed in, then maybe I could try to make a more minimal reproducer that I can share?

Exact steps for others to reproduce the error

None yet. Hopefully coming soon.

**System Information** Operating system: Linux Graphics card: Intel **Blender Version** Broken: 2.92 **Short description of error** I have a `.blend` file where any basic edit like moving an object between collections seems to cause a freeze lasting several seconds to a minute, with the following output in the terminal: ``` Using fallback Using fallback Using fallback Using fallback Using fallback Using fallback Using fallback Using fallback Using fallback Using fallback ``` I don't think I can share the file, and the slow nature of the freeze and vagueness of the error report make it an unappealing prospect to try to narrow the bug down with no further information. However, if someone familiar with the code could say what kind of circumstances this error message gets printed in, then maybe I could try to make a more minimal reproducer that I can share? **Exact steps for others to reproduce the error** None yet. Hopefully coming soon.

Will commented

2021-04-13 18:48:55 +02:00

Added subscriber: @WCN

Will commented

2021-04-13 18:55:58 +02:00

Okay— Actually, "Using fallback" seems to be caused by Boolean modifier in 'FAST' mode with overlapping geometry, and the slow performance may be caused by that geometry being fairly poly-heavy and then being propagated along a series of other Boolean modifiers.

So I'm not sure whether this is a bug— the "Using fallback" behaviour does produce performance that's unusably slow (tantamount to a program freeze) even though the Boolean usually works fast enough to be msotly interactive, but I don't know what the expected behaviour is.

Okay— Actually, "Using fallback" seems to be caused by Boolean modifier in `'FAST'` mode with overlapping geometry, and the slow performance may be caused by that geometry being fairly poly-heavy and then being propagated along a series of other Boolean modifiers. So I'm not sure whether this is a bug— the "Using fallback" behaviour does produce performance that's unusably slow (tantamount to a program freeze) even though the Boolean usually works fast enough to be msotly interactive, but I don't know what the expected behaviour is.

Germano Cavalcante commented

2021-04-16 20:55:42 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-04-16 20:55:42 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Germano Cavalcante commented

2021-04-16 20:55:42 +02:00

Thanks for the report, but unfortunately this can't be triaged as a complete bug report.

For the development team to be able to help, there needs to be reproducible steps (start blender, press this, then that ...).

Remind that potential performance improvements are not handled as bug reports.

To improve performance, consider using less complex geometry, simpler shaders and smaller textures.

Thanks for the report, but unfortunately this can't be triaged as a complete bug report. For the development team to be able to help, there needs to be reproducible steps (start blender, press this, then that ...). Remind that potential performance improvements are not handled as bug reports. To improve performance, consider using less complex geometry, simpler shaders and smaller textures.

Will commented

2021-04-16 21:30:51 +02:00

I was hoping that someone would provide information which would make it easier for me to figure out reproduction steps.

If there is an abnormal issue here, I think it'd be more of a performance regression than a potential performance improvement. The "Using fallback" behaviour seems orders of magnitude slower than usual behaviour.

That said, the geometry I'm using is also pretty heavy, and I'm not sure how I would produce a simpler reproducer from it or narrow it down, so I'll just go ahead and close this report for now.

I was hoping that someone would provide information which would make it easier for me to figure out reproduction steps. If there is an abnormal issue here, I think it'd be more of a performance regression than a potential performance improvement. The "Using fallback" behaviour seems orders of magnitude slower than usual behaviour. That said, the geometry I'm using is also pretty heavy, and I'm not sure how I would produce a simpler reproducer from it or narrow it down, so I'll just go ahead and close this report for now.

Will commented

2021-04-16 21:31:01 +02:00

Changed status from 'Needs User Info' to: 'Archived'

Will closed this issue

2021-04-16 21:31:01 +02:00

Alex Zhornyak referenced this issue

2023-08-01 05:28:51 +02:00

[Python API] PointerProperty to type Collection slows down animation after open Preferences with excluded collections #110669

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