Bug 465441

Summary:	plasmashell leaks memory after each resume (currently around 23 GB) [with heaptrack] in plasmadesktoptheme.cpp:231
Product:	[Plasma] plasmashell	Reporter:	Szőts Ákos <akos+kde>
Component:	generic-performance	Assignee:	Plasma Bugs List <plasma-bugs>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	arisu+kdebugs, bebl, cyberbeat, dga231, kde-bugs.ojiug, nate
Priority:	NOR
Version First Reported In:	5.26.5
Target Milestone:	1.0
Platform:	openSUSE
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	23 GB leak Flame graph Top leakers Top-down 30 GB Plasma leak

Description Szőts Ákos 2023-02-07 19:28:29 UTC

Created attachment 156038 [details]
23 GB leak

Plasmashell, after 3-4 sleep resume cycles, starts leaking memory. In the first 3-4 cycles just some hundred MBs but then after +5 GB, then +15 GB.

Heaptrack shows the following backtrace as one of the culprits:

main in plasmashell
QCoreApplication::exec() in libQt5Core.so.5
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) in libQt5Core.so.5
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) in libQt5Core.so.5
g_main_context_iteration in libglib-2.0.so.0
g_main_context_iterate in libglib-2.0.so.0
g_main_context_dispatch in libglib-2.0.so.0
g_main_dispatch in libglib-2.0.so.0
postEventSourceDispatch in libQt5Core.so.5
QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) in libQt5Core.so.5
QCoreApplication::notifyInternal2(QObject*, QEvent*) in libQt5Core.so.5
QApplicationPrivate::notify_helper(QObject*, QEvent*) in libQt5Widgets.so.5
QObject::event(QEvent*) in libQt5Core.so.5
PlasmaDesktopTheme::syncWindow() in org.kde.desktop.so
QMetaObject::Connection QObject::connect<void (QQuickWindow::*)(), void (PlasmaDesktopTheme::*)()>(QtPrivate::FunctionPointer<void (QQuickWindow::*)()>::Object const*, void (QQuickWindow::*)(), QtPrivate::FunctionPointer<void (PlasmaDesktopTheme::*)()>::Object const*, void (PlasmaDesktopTheme::*)(), Qt::ConnectionType) in org.kde.desktop.so
QObject::connectImpl(QObject const*, void**, QObject const*, void**, QtPrivate::QSlotObjectBase*, Qt::ConnectionType, int const*, QMetaObject const*) in libQt5Core.so.5
QObjectPrivate::connectImpl(QObject const*, int, QObject const*, void**, QtPrivate::QSlotObjectBase*, Qt::ConnectionType, int const*, QMetaObject const*) in libQt5Core.so.5

According to it, the leaking line is plasmadesktoptheme.cpp:231:

if (qw) {
    connect(qw, &QQuickWindow::sceneGraphInitialized, this, &PlasmaDesktopTheme::syncWindow);
}

Heaptrack file: https://mega.nz/file/lRJFmSCC#olTMN_Kqf8Cv1l2OlKDzZ_lYoQSWkSisL2JGQ_z7j3I

Please, take a look whether you can find other problems, too. Thank you!

Operating System: openSUSE Tumbleweed 20230130
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.102.0
Qt Version: 5.15.8
Kernel Version: 6.1.8-1-default (64-bit)
Graphics Platform: X11
Memory: 78.5 GiB of RAM

Comment 1 Szőts Ákos 2023-02-07 19:28:57 UTC

Created attachment 156039 [details]
Flame graph

Comment 2 Szőts Ákos 2023-02-07 19:29:09 UTC

Created attachment 156040 [details]
Top leakers

Comment 3 Szőts Ákos 2023-02-07 19:29:19 UTC

Created attachment 156041 [details]
Top-down

Comment 4 Sebastian 2023-06-10 10:54:25 UTC

This sounds like exactly the issue I am experiencing as well, except that it only starts occuring after about 20 sleep/resume cycles. 

I have the impression the leak is exponential though, the first few cycles the memory increases as well, but barely noticeable (<50 MB), then after about 20 cycles it increases to 1 GB, then each cycle to 1.5 / 2.5 / 4.3 / 8.0 GB. 

It does not seem to matter how much time passed between sleep and resume.

heaptrack does not seem to show anything out of the ordinary, but I am probably not reading it right.

My system:
Operating System: Ubuntu Studio 22.04
KDE Plasma Version: 5.24.7
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.3
Kernel Version: 5.19.0-1024-lowlatency (64-bit)
Graphics Platform: X11
Processors: 12 × AMD Ryzen 5 1600X Six-Core Processor
Memory: 15.6 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 3060/PCIe/SSE2

Comment 5 Szőts Ákos 2023-07-07 19:22:19 UTC

Created attachment 160131 [details]
30 GB Plasma leak

Just wanted to confirm that in the latest version it's still an issue.

Operating System: openSUSE Tumbleweed 20230603
KDE Plasma Version: 5.27.5
KDE Frameworks Version: 5.106.0
Qt Version: 5.15.9
Kernel Version: 6.3.4-1-default (64-bit)
Graphics Platform: X11
Processors: 16 × AMD Ryzen 7 3700X 8-Core Processor

Comment 6 Nate Graham 2025-05-14 19:19:15 UTC

Thanks for the bug report! I'm really sorry that we weren't able to get to it before now. A lot has changed since then, including a new Plasma major version backed by a new Qt major version.

Are you able to see if the issue still happens on Plasma 6.3.5 or later?

Thanks a lot!

Comment 7 Szőts Ákos 2025-05-14 19:35:41 UTC

No, I haven't seen it recently.