Cycles slows down gradually when rendering multiple times(not related to temperature) #114671

New Issue

Ahmet-Dara-Vefa · 2023-11-09T15:00:15+01:00

Ahmet-Dara-Vefa commented

2023-11-09 15:00:15 +01:00

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1060 3GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 527.56

Blender Version
Broken: version: 3.6.0, branch: blender-v3.6-release, commit date: 2023-06-27 08:08, hash: c7fc78b81ecb
Broken: version 4.0.0 beta v40(november 9 release) commit link-> https://projects.blender.org/blender/blender/commit/aaf69376314f
Worked: -

Short description of error
Cycles render times gradually get worse when rendering repeatedly. This is not because of heating as the problem continues if you stop the renders and restart it after a while.
Rendering an empty scene repeatedly starts at around 0.07 seconds and keeps increasing gradually to 0.08-0.09-0.10(I recorded up to 0.54). After stopping for a while and restarting the renders, it still continues from around the last interval, it never drops back.
Issue persists when using either CPU or GPU
This is not the case in Eevee.
The only solution I found was restarting blender.

Exact steps for others to reproduce the error
Either use the attached blend file or follow until step9:

open blender
switch engine to cycles
set render samples to 1
turn off "Denoise"
turn off "Use Tiling"
turn on "Persistent Data"(issue continues with persistent data turned on or off)
set render resolution to 128x128
remove everything from the scene except the camera
toggle System Console on
in the scripting panel, create a new file, attach the following code which renders the scene multiple times until you press keyboard interrupt(ctrl + C) on system console
run script
while rendering, observe the render times increase gradually.
interrupt execution
Wait a bit and go back to step 11
restart blender and go back to step 9, you'll see the render times become normal again.

Feel free to test on CPU or GPU or with eevee(eevee works correctly)

import bpy
import os, tempfile
tmp = tempfile.NamedTemporaryFile(delete=False, suffix='.png')
try:
    bpy.context.scene.render.filepath = tmp.name

    while True:
        bpy.ops.render.render(write_still = True)

finally:
    tmp.close()

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce GTX 1060 3GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 527.56 **Blender Version** Broken: version: 3.6.0, branch: blender-v3.6-release, commit date: 2023-06-27 08:08, hash: `c7fc78b81ecb` Broken: version 4.0.0 beta v40(november 9 release) commit link-> https://projects.blender.org/blender/blender/commit/aaf69376314f Worked: - **Short description of error** Cycles render times gradually get worse when rendering repeatedly. This is not because of heating as the problem continues if you stop the renders and restart it after a while. Rendering an empty scene repeatedly starts at around 0.07 seconds and keeps increasing gradually to 0.08-0.09-0.10(I recorded up to 0.54). After stopping for a while and restarting the renders, it still continues from around the last interval, it never drops back. Issue persists when using either CPU or GPU This is not the case in Eevee. The only solution I found was restarting blender. **Exact steps for others to reproduce the error** Either use the attached blend file or follow until step9: 1. open blender 2. switch engine to cycles 3. set render samples to 1 4. turn off "Denoise" 5. turn off "Use Tiling" 6. turn on "Persistent Data"(issue continues with persistent data turned on or off) 7. set render resolution to 128x128 8. remove everything from the scene except the camera 9. toggle System Console on 10. in the scripting panel, create a new file, attach the following code which renders the scene multiple times until you press keyboard interrupt(ctrl + C) on system console 11. run script 12. while rendering, observe the render times increase gradually. 13. interrupt execution 14. Wait a bit and go back to step 11 15. restart blender and go back to step 9, you'll see the render times become normal again. Feel free to test on CPU or GPU or with eevee(eevee works correctly) ``` import bpy import os, tempfile tmp = tempfile.NamedTemporaryFile(delete=False, suffix='.png') try: bpy.context.scene.render.filepath = tmp.name while True: bpy.ops.render.render(write_still = True) finally: tmp.close() ```

cycles gradual slowdown bug.blend

890 KiB

Ahmet-Dara-Vefa added the

labels 2023-11-09 15:00:15 +01:00

Germano Cavalcante commented

2023-11-09 17:02:01 +01:00

Thanks for the report, I can confirm it, although the difference is very subtle:
00:00.03 to 00:00.08 after 5 minutes

This report reminded me of this other one:
#112830: Program lags after iterative script calls to bpy.ops.render when using Cycles renderer

This other one, however, is much more obvious, affects viewport in general but only affects Windows (not Linux).

**System Information**
Operating system: Windows-10-10.0.23580-SP0 64 Bits
Graphics card: AMD Radeon(TM) Graphics ATI Technologies Inc. 4.6.0 Core Profile Context 23.20.13.01.230915
version: 4.1.0 Alpha

Thanks for the report, I can confirm it, although the difference is very subtle: `00:00.03` to `00:00.08` after 5 minutes This report reminded me of this other one: #112830: Program lags after iterative script calls to bpy.ops.render when using Cycles renderer This other one, however, is much more obvious, affects viewport in general but only affects Windows (not Linux). ``` **System Information** Operating system: Windows-10-10.0.23580-SP0 64 Bits Graphics card: AMD Radeon(TM) Graphics ATI Technologies Inc. 4.6.0 Core Profile Context 23.20.13.01.230915 version: 4.1.0 Alpha ```

Germano Cavalcante added

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Cycles slows down gradually when rendering multiple times(not related to temperature) #114671