Bug 462277

Created attachment 154051 [details]
kwin support information

SUMMARY
When a window is opened, kwin seems to allocate some memory to store its icon. However, this memory is not freed when the window is closed.

heaptrack output: https://drive.google.com/file/d/1xkhCrdzyPWCX6wtRDGubhhkyOfE-jeaN/view?usp=sharing (it is too big to attach here, 5 MB)

STEPS TO REPRODUCE
1. `heaptrack kwin_x11 --replace`
2. Run the following loop in bash:
```
while true
do
    sleep 5
    dolphin &
    sleep 5
    killall dolphin -u kishore
done
```
3. Wait for some time
4. Kill kwin.
5. `heaptrack_gui $name_of_output_file`

OBSERVED RESULT
Kwin's memory usage grows linearly with time (heaptrack output attached). The backtrace to which heaptrack associates most of the memory is:
```
readIcon in libKF5WindowSystem.so.5
NETWinInfo::update(QFlags<NET::Property>, QFlags<NET::Property2>) in libKF5WindowSystem.so.5
KWin::WinInfo::WinInfo(KWin::X11Window*, unsigned int, unsigned int, QFlags<NET::Property>, QFlags<NET::Property2>) in libkwin.so.5
KWin::X11Window::manage(unsigned int, bool) in libkwin.so.5
KWin::Workspace::createX11Window(unsigned int, bool) in libkwin.so.5
KWin::Workspace::workspaceEvent(xcb_generic_event_t*) in libkwin.so.5
QAbstractEventDispatcher::filterNativeEvent(QByteArray const&, void*, long*) in libQt5Core.so.5
QXcbConnection::handleXcbEvent(xcb_generic_event_t*) in libQt5XcbQpa.so.5
QXcbConnection::processXcbEvents(QFlags<QEventLoop::ProcessEventsFlag>) in libQt5XcbQpa.so.5
<unresolved function> in libQt5XcbQpa.so.5
g_main_context_dispatch in libglib-2.0.so.0
<unresolved function> in libglib-2.0.so.0
g_main_context_iteration in libglib-2.0.so.0
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) in libQt5Core.so.5
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) in libQt5Core.so.5
QCoreApplication::exec() in libQt5Core.so.5
main in kwin_x11
```

EXPECTED RESULT
Memory usage should reach steady state after some time.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.26.3
KDE Frameworks Version: 5.100.0
Qt Version: 5.15.7
Kernel Version: 5.15.79-1-lts (64-bit)
Graphics Platform: X11
Graphics Processor: virgl
Manufacturer: QEMU

ADDITIONAL INFORMATION
A. I'm not sure if the same thing happens on Wayland.

B. I installed debug symbols for kwin and kwindowsystem.

C. kwin support information (`qdbus org.kde.KWin /KWin supportInformation`) is attached

D. heaptrack output: https://drive.google.com/file/d/1xkhCrdzyPWCX6wtRDGubhhkyOfE-jeaN/view?usp=sharing (it is too big to attach here, 5 MB)