VSE: Prefetch Cache makes Blender hang #79497

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: Intel(R) UHD Graphics 600 Intel 4.5.0 - Build 26.20.100.7262

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-08-03 05:14, hash: 144f780c71

Short description of error
Using Prefetch cache makes Blender highly unstable and then hang.

Exact steps for others to reproduce the error

Play some edited video in the Sequencer which the Prefetch cache can't keep up with.
Move the cursor out of Blender and then back(?)
The wait-mouse-cursor will show, the screen will go milky-white and then Blender hangs.

[.blend and video removed, as it was not considered useful]

Added subscriber: @tintwotin

#79508 was marked as duplicate of this issue

Added subscriber: @iss

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

Does this happen when you click on File > Defaults > Load Factory Settings? Also aren't you running out of RAM? I see playhead skipping over cached areas, also the lag when turning on prefetch is quite suspicious.

Can not reproduce crash though. Can you run Blender via blender_debug_log.cmd file and look into blender_debug_output.txt file that will be created. In the end there should be crash file mentioned. Can you upload I guess all those files?

Goes unresponsive until Windows suggests to shut Blender down:

[reports removed, as they were not considered useful]

I hope you noticed I've uploaded the .blend above, so you can try for yourself.

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

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

I have tried to reproduce with provided .blend file.

Thanks for crash backtrace, it looks I accidentally removed previous fix for this in refactoring patch.

Now I am not sure why it is executed, but this crash is caused by running delete operator. I guess this could be caused by some addon?

This issue was referenced by 1ccb997c6d

Changed status from 'Confirmed' to: 'Resolved'

Added subscriber: @lichtwerk

This problem is not solved in the 2.91 Alpha build from last night(which includes the "delete" fix). Tested by using the same .blend above. First playing without Prefetch Cache and then with - it ends up milky-white and hanging:

[video removed, as it was not considered useful]

Can you then upload new crash file? The one you gave me crashed in delete operator

Actually, it doesn't seem to produce a crash report - as shown in the video, it hangs until the process is killed.

Debug logs:
[reports removed, as they were not considered useful]

As this bug-report is now closed and it seems to be unrelated to the delete bug, do I have to make a new report, or can this one be reopened?

Probably it would be better to make new report. But please make sure you test this without addons. This could be even issue with GPU somehow, there are some issues with intel GPUs not working optimally, so make sure you have latest drivers as well.

This is the same bug, as this user encountered here: https://youtu.be/56XaahF5QMw?t=237
It's still not fixed.

As matter of fact if I play the same file in 2.79 it plays with 24 fps, if I play the same file with Prefetch Frames ON in 2.92 it only plays 7-10 fps.

I don't see any connection between posted video and this particular report. If there is bug please create new report.

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VSE: Prefetch Cache makes Blender hang #79497