[Digikam-devel] [digikam] [Bug 324917] New: digikam-3.4:=?UTF-8?Q?=20loading=20of=20tag=20icons=20fails=20=E2=86=92=20very=20high=20CPU=20usage=20and=20freezing=20GUI=20?=[callgrind]

[Frank Steinmetzger]

https://bugs.kde.org/show_bug.cgi?id=324917

            Bug ID: 324917
           Summary: digikam-3.4: loading of tag icons fails → very high
                    CPU usage and freezing GUI [callgrind]
    Classification: Unclassified
           Product: digikam
           Version: 3.4.0
          Platform: Gentoo Packages
                OS: Linux
            Status: UNCONFIRMED
          Severity: grave
          Priority: NOR
         Component: Tags
          Assignee: digikam-devel at kde.org
          Reporter: Warp_7 at gmx.de

Hello

I upgraded from 3.2 to 3.4 today. When I opened digikam afterwards, the GUI was
extremely sluggish, moving the mouse over anything took very long and CPU load
was always 100% on one core.

I managed to narrow it down to the tags tree. If it is not visible, then
browsing works fast as usual, albeit still generally a bit slow-ish. If I open
the tag filter sidebar, then digikam hangs for a while and then returns to
normal. It will also hang if I move the mouse over the tag tree. If I open the
tag editing sidebar, then browsing images becomes very slow, too, because the
tree needs to be updated for every image.

Also, instead of the usual icons, I have question mark icons in front of all
tags.

So it seems something is very wrong with loading tag information. For
profiling, I loaded digikam into valgrind and opened the tag filter sidebar. I
waited for it to open and settle down in terms of CPU load. Then I enabled
callgrind through SSH (so I don't have to switch programs which would fudge the
measurement) and only moved the mose a bit over the tag tree. Once the CPU load
had settled again, I switched callgrind off. See attached KCacheGrind’s output
for the measurement.

It seems that loading icons for the tags is the problem...
99.7% of the time that the CPU spends heating my room is in
KIconLoader::loadIcon.
The database used has 199 tags, 13002 images and 16696 imagetags.

I rebuild digikam with debug symbols enabled. So if you want me to debug more
specifically, please let me know.

Reproducible: Always

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