Investigating thumbnail.so (kioworker) 100% CPU

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1

Hello all,

Before filing a bug, I want to investigate more about a problem with kioworker/thumbnail.so.

My setup is the following:

  • Plasma 6.3.5 on Archlinux
  • Thinkpad T14s, Ryzen 7 PRO 6850U, Ram 30GiB, 1TB storage with btrfs (on top of luks)
  • KDE startup configured to “new session” (do not re-open apps)
  • Dolphin thumbnails disabled (i.e., all checkbox unticked under “Thumbnail” tab in Dolphin config)
  • KDE file indexing disabled

If I do the following:

  • Boot my laptop
  • Login to plasma with my user
  • Open Konsole and execute “top”

I find out that

/usr/lib/kf6/kioworker /usr/lib/qt6/plugins/kf6/kio/thumbnail.so thumbnail  local:/run/user/1000/plasmashellDMLlBQ.4.kioworker.socket

Uses 100% of CPU.

Now, if I understand correctly, this process “just” computes thumbnails for files to be later showed quickly in dolphin. But then, is it expected for it to run in background (after boot, I do not open Dolphin)? Why it’s running even after disabling thumbnails? Why it uses 100% of CPU? It will continue using 100% CPU until I kill it, no matter how long I wait.

But more importantly, how can I debug this? How can I find on which folder/file it stucks? journalctl shows nothing about it.

2

Thats definitely a bug. Can you try pressing F12 in Dolphin, which is the thumbnails on/off switch?
Does pressing that help? Also, if you enable at least one preview, does that help?

In either case, I think theres not much else to do to investigate this further than building dev debug session. So please report a bug and link here, I will add it to my to-do list :slight_smile:

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3

From a clean boot, I tried pressing F12. That switches the thumbnails (i see icons change size) but have no effect on kioworker/thumbnail process.

Did the same (without rebooting) with just “Images (GIF/PNG/…)” ticked, and nothing changed (even if i press F12).

Is frameworks-kio/general the correct product/section in kde bugtracker?

Thanks!!

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4

Yeah that should be correct. We can always move things around if not.

5

Bug filed!

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