Is there a way to view current thumbnail cache max size and tweak it? When I open a folder containing wallpapers for example in dolphin, thumbnails start to be generated and are available if I come back to it later. However, once in a while if I’ve left the computer on overnight or it wakes up from sleep, and I navigate back to the folder, the thumbnails have to be regenerated, thus the question about cache size and increasing it.
I found this article about gnome and Nautilus Increase thumbnail cache in Ubuntu , but either my search terms were not targeted enough or I missed something when trying to find the equivalent for dolphin.
Related to this, the thumbnails seem to be generated one by one, is there a parallel option I can turn on, or is that a new feature request?
I took a look at the standards list you linked to and Deleting Thumbnails | Thumbnail Managing Standard is related to deletion of thumbnails. I also took a look at ~/.cache/thumbnails and still have thumbnails from 2025.
Thumbnail Saving | Thumbnail Managing Standard is interesting because if I understand it correctly, the filename of thumbnail is an MD5 hash of the absolute path to file, so if a file is renamed or moved, thumbnail is generated again?
In other words specifically for dolphin:
Thumbnails are never deleted
Thumbnails are regenerated if the original file is moved/edited or renamed?
Is that correct? Do you know where I could look for more information about how gwenview handles thumbnails?
Correct, both could be improved…
That’s just developer time required and priorisation…
To be clear, I know for a fact Gwenview doesn’t cache anything on disk neither read from disk thumbnails. It keeps thumbnails in memory for a while. Not sure how many thumbnails or for how long.
I don’t think you can regenerate thumbnails. When I open a folder, dolphin(?) seems to fire off requests in the following format:
/usr/lib/kf6/kioworker /usr/1ib/qt6/plugins/kf6/kio/thumbnail.so thumbnail "Socket pointing to file?"
Probably find out if there is an existing thumbnail for your picture and delete it to force dolphin to regenerate it:
#This should hopefully give you the name of thumbnail
import hashlib, urllib.parse, os
file = "/path/to/your/image.jpg"
uri = "file://" + urllib.parse.quote(os.path.abspath(file))
print(hashlib.md5(uri.encode()).hexdigest() + ".png")
The other thing to check is going to Configure → Configure Dolphin → Interface → Previews and ensure that the file type that you want a thumbnail for is ticked.