Bug 499476

Summary:	Gwenview generates thumbnails for every image file in a folder when opening a picture even when it doesn't make much sense to do so
Product:	[Applications] gwenview	Reporter:	hazelnot <hazelnot>
Component:	general	Assignee:	Gwenview Bugs <gwenview-bugs-null>
Status:	REOPENED ---
Severity:	normal	CC:	john.kizer
Priority:	NOR
Version First Reported In:	24.12.1
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description hazelnot 2025-02-03 19:32:49 UTC

SUMMARY
Gwenview spends a lot of time generating thumbnails for every image in the folder when opening a picture, even when it doesn't make much sense to do so. My screenshots folder is 4.3 GB in size, contains about 3600 files, and is stored on a hard drive to not use up SSD space for something speed isn't really *that* important. This slows it down to a crawl and often makes me thing it's frozen, because it usually doesn't let me do anything until it's finished generating thumbnails for all 3600 files.

I get why it would do this, but I feel it doesn't make that much sense to generate them ahead of time in case the user decides to open the thumbnails panel. I personally never do, so this just ends up being an inconvenience and makes the app feel a lot slower than it should for a simple image viewer.

STEPS TO REPRODUCE
1. Open a file in a folder with a lot of pictures, especially one stored on a hard drive
2. Have the "Show Thumbnails" pane closed

OBSERVED RESULT
Gwenview spends a really really long time generating thousands of thumbnails from an old hard drive, making it inconvenient to use for something like, say, a screenshots folder I've carried across distrohops and OS reinstalls

EXPECTED RESULT
My suggestion would be to only start generating thumbnails when the thumbnails panel is opened 

SOFTWARE/OS VERSIONS
Linux: EndeavourOS
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1

Comment 1 John Kizer 2025-02-10 22:23:11 UTC

Hi - my understanding is that the situation you're describing is what the "Low resource usage mode" is designed to help with, located under Configure Gwenview > Advanced.

If you toggle that option on, do you still experience that lengthy time generating thumbnails?

(In general, I would assume that producing thumbnails the first time a folder is opened is desirable, since for most images it would only be needed once, and would significantly speed up maneuvering that folder later)

Comment 2 Bug Janitor Service 2025-02-25 03:46:48 UTC

🐛🧹 ⚠️ This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information, then set the bug status to REPORTED. If there is no change for at least 30 days, it will be automatically closed as RESOLVED WORKSFORME.

For more information about our bug triaging procedures, please read https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging.

Thank you for helping us make KDE software even better for everyone!

Comment 3 Bug Janitor Service 2025-03-12 03:47:26 UTC

🐛🧹 This bug has been in NEEDSINFO status with no change for at least 30 days. Closing as RESOLVED WORKSFORME.

Comment 4 hazelnot 2025-06-23 18:32:42 UTC

It seems like now even with "Low resource usage mode" it still indexes every file in the folder, meaning I have to wait for several minutes to index my entire screenshots folder (which is now close to 4000 files, on the same old hard drive), just to look at a single image. I'm not sure if this is a bug or if now this happens even with that enabled, but Gwenview is now pretty much completely unusable for me.

Comment 5 hazelnot 2025-06-23 18:34:13 UTC

It also not only happens the first time a folder is opened, but every single time any file in that folder is opened, even while another instance of Gwenview with another file from there is open right beside it.