Bug 503940

SUMMARY

When Gwenview displays an image in View mode in a directory w/ many large video files, it displays the image, but immediately becomes unresponsive due to 100% CPU. This can last for 10+ seconds, depending on the total filesize of the videos.

STEPS TO REPRODUCE
1. Make sure Gwenview settings -> General -> "Show videos" is selected
2. Place any image file in a directory w/ many large video files
3. Load image in View mode, e.g. in terminal: "gwenview dir/image.png"

OBSERVED RESULT

Gwenview displays image but is unresponsive, 100% CPU for 5+ seconds, then CPU drops to normal

EXPECTED RESULT

Gwenview displays image w/o extended max CPU

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: 
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.8.3

ADDITIONAL INFORMATION

This issue is somewhat new, although I can't be specific. Appeared within the past several months.

Gwenview works normally if the "Show videos" setting is off. The "Automatically play" setting doesn't make a difference.

Gwenview also works normally if you navigate in Browse mode to the directory, then load the image. That is, running "gwenview dir" then selecting and loading the image works fine. Only "gwenview dir/image.png" causes the issue.

Experimented w/ different numbers of video files. Here is how long the 100% CPU lasted in different scenarios:

- 12 sec in directory (a), 1,800 videos (61 GiB)
- 30 sec in directory (b), 650 videos (24 GiB)
- 75 sec in directory (c), 620 videos (54 GiB)

I moved the contents of (b) and (c) into new directory (d), and CPU was maxed for 100 sec. The effect seems to be associated w/ particularly large video files, rather than many small video files.

iotop doesn't show a spike in activity, neither read nor write. Regular top or ps shows 100% cpu but no huge memory usage: in my case, w/ 16 GiB of memory, top showed %mem ranging between 1% and 2%.