https://bugs.kde.org/show_bug.cgi?id=522851
Bug ID: 522851
Summary: Gwenview freezes/is killed (SIGABRT) due to
synchronous Exiv2 read in SortedDirModel::lessThan on
slow/remote filesystems
Classification: Applications
Product: gwenview
Version First 26.04.3
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: crash
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 194145
--> https://bugs.kde.org/attachment.cgi?id=194145&action=edit
Full coredumpctl backtrace (all threads)
DESCRIPTION
When browsing a folder mounted via a slow/remote filesystem (in my case,
an rclone FUSE mount of a cloud storage provider - pCloud), Gwenview
becomes unresponsive and is eventually killed with SIGABRT by the desktop
environment's "application not responding" watchdog.
The crash consistently occurs while Gwenview is listing/sorting the
parent directory, not specifically on window close as it might first
appear (timing coincidence - see STEPS TO REPRODUCE).
ROOT CAUSE (from coredump analysis)
SortedDirModel::lessThan() calls TimeUtils::dateTimeForFileItem(),
which calls TimeUtils::CacheItem::updateFromExif(), which calls
Exiv2ImageLoader::load(), which performs a synchronous, blocking
fread()/read() directly on the file path — bypassing KIO entirely,
even though the directory listing itself (KCoreDirListerCache)
correctly uses KIO's asynchronous worker mechanism.
On a local filesystem this read is fast enough to be invisible. On a
FUSE-mounted remote filesystem (rclone mount, vfs-cache-mode writes),
this read can take several seconds per file, and since it runs on
the main/UI thread, it blocks Gwenview's event loop entirely — with
no loading indicator shown to the user, since the thread responsible
for drawing one is the same thread that is blocked.
This appears to be a case of the same underlying architectural issue
documented in KDE bug 423187 (Dolphin freezes on FUSE/slow mounts),
but occurring inside Gwenview's own sort comparator rather than in
KIO/Dolphin itself.
Note: this is technically a forced kill (SIGABRT sent externally)
rather than an application-internal crash (no segfault, no C++
exception) — but it is filed as "crash" severity since the visible
end result is a killed process with a coredump, not just a temporary
freeze.
STEPS TO REPRODUCE
1. Mount a remote filesystem via FUSE (e.g. rclone mount) containing
a folder with multiple JPEG images with EXIF data
2. Open any image from that folder in Gwenview
3. Wait a few seconds for Gwenview to load/sort the folder in the
background (thumbnail bar population reading EXIF data for each file)
4. Close the Gwenview window while this background sort is still in
progress (or simply wait/interact with the app during this window)
OBSERVED RESULT
Gwenview becomes unresponsive with no loading indicator, then is
killed (SIGABRT) by the desktop's hang detection. This is reproducible
consistently on the same folder.
EXPECTED RESULT
EXIF reads used for sorting/date purposes should be performed
asynchronously (e.g. via KIO, or on a worker thread), consistent
with how the directory listing itself is already handled, so slow
filesystems don't block the Gwenview UI thread. At minimum, a loading
indicator should be shown, and the application should not be killed
for legitimate (if slow) I/O operations.
SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 44
KDE Plasma Version: 6.7.2
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
Kernel Version: 7.1.3-200.fc44.x86_64 (64-bit)
Graphics Platform: Wayland
Gwenview Version: 26.04.3-1.fc44
ADDITIONAL INFORMATION
Remote filesystem setup: rclone mount (pCloud backend, EU region),
mounted via systemd user service with --vfs-cache-mode writes
--dir-cache-time 720h.
Reproduced consistently across multiple attempts with different PIDs,
all showing the identical crashing thread backtrace:
#7 read()
#8 _IO_file_underflow
#9 _IO_file_xsgetn
#10 _IO_fread
#11 Exiv2::isJpegType
#12 Exiv2::ImageFactory::open
#13 Exiv2::ImageFactory::open (string overload)
#14 Gwenview::Exiv2ImageLoader::load
#15 Gwenview::TimeUtils::CacheItem::updateFromExif
#16 Gwenview::TimeUtils::dateTimeForFileItem
#17 Gwenview::SortedDirModel::lessThan
#18 QSortFilterProxyModelGreaterThan::operator()
...
#27 KDirModelPrivate::_k_slotNewItems
#29 KCoreDirLister::itemsAdded
#31 KCoreDirListerCache::slotEntries
#33 KIO::ListJob::entries
#36 KIO::WorkerInterface::dispatch
Full coredump backtrace (all threads) available on request; happy to
attach as a file if useful.
See also: https://bugs.kde.org/show_bug.cgi?id=423187 (related
architectural issue in Dolphin with FUSE/slow mounts)
This crash keeps repeating. I'm not a developer, this report was completed with
the assistance of Claude AI.
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