[dolphin] [Bug 499551] Dolphin hangs when opening context menu for directory with many files or for a huge file selection

[Méven]

https://bugs.kde.org/show_bug.cgi?id=499551

--- Comment #8 from Méven <meven at kde.org> ---
(In reply to Méven from comment #7)
> (In reply to Andrea Ippolito from comment #6)
> > Comment on attachment 178009 [details]
> > flamegraph
> 
> Very Nice that's helpful.
> > 
> > this is while opening the context menu on a directory containing 30k 4KB
> > .bin files generated with:
> > 
> > #!/bin/bash
> > 
> > dd if=/dev/urandom of=/tmp/file-gen/file-random-0.bin bs=4K count=1
> > iflag=fullblock
> > for i in $(seq 1 30000);
> > do
> >     cp /tmp/file-gen/file-random-0.bin /tmp/file-gen/file-random-$i.bin
> > done
> 
> You are missing some debug symbols but that's interesting already.
> We can see the time is spent by the context menu plugin
> slideshowfileitemaction which is part of gwenview and not enabled by default
> IIRC.
> 
> It is clearly due to:
> https://invent.kde.org/graphics/gwenview/-/blob/master/app/
> slideshowfileitemaction.cpp?ref_type=heads#L49
> 
> There are no images in the folder and the files are of random type.
> This can be optimized, it uses `db.mimeTypeForFile` which opens files when
> it can't determine the mimetype by extension.

That's not true it uses `QMimeDatabase::MatchExtension`.

> It should use filename extension only.

The optimization would be to limit the time spent in this directory scanning.
If there is 1 image among 10 000 non-image files or ~275k we don't really care.

> This might look a bit like an edge case, but I think KDE software should be efficient enough to handle it, it's a situation that can happen IRL.

275K not that often.
I am guessing that can happen in some research fields or development, data
mining and other cases which we want to enable of course.

-- 
You are receiving this mail because:
You are on the CC list for the bug.