Bug 423594 - Notifications spike the CPU and consume extra memory when they appear; can freeze the system when many notifications are received all together
Summary: Notifications spike the CPU and consume extra memory when they appear; can fr...
Alias: None
Product: plasmashell
Classification: Plasma
Component: Notifications (show other bugs)
Version: 5.19.2
Platform: Archlinux Linux
: VHI normal
Target Milestone: 1.0
Assignee: Kai Uwe Broulik
: 398117 418205 418442 422370 433775 435506 (view as bug list)
Depends on:
Reported: 2020-06-27 17:31 UTC by xdmx
Modified: 2021-09-23 17:57 UTC (History)
12 users (show)

See Also:
Latest Commit:
Version Fixed In: 5.21.0


Note You need to log in before you can comment on or make changes to this bug.
Description xdmx 2020-06-27 17:31:57 UTC
I have a standard KDE installation under Arch, I've noticed that when I receive a lot of notifications, for example from KDE connect when someone starts sending me dozens of images, the cpu of my laptop (Lenovo X1 Carbon) goes up to 100% and everything starts lagging. Then plasmadesktop's memory increases and sometimes it uses 900mb and I have to kill and restart it.

1. Connect KDE connect (I use Android, but it shouldn't matter)
2. Ask someone to send you a lot of messages all together (usually photos)
3. See plasmadesktop memory/cpu increase

It's painful :)

It shouldn't lag so much when many notifications are received, may it should delay the notification to group them, or notify only one of them. And most important it should have memory leaks

Linux/KDE Plasma: Arch 5.19.2
KDE Plasma Version: 5.19.2
KDE Frameworks Version: 5.71
Qt Version: 5.15
Comment 1 Nate Graham 2020-07-02 00:43:32 UTC
I've had this happen as well. Here's how I can reproduce it:

1. Open Telegram
2. Put the computer to sleep
3. Receive hundreds of messages in Telegram
4. Wake up and unlock the computer

Plasmashell will then receive a flood of notifications from Telegram that spikes the CPU and memory usage, and can even render the shell frozen for a period of time.
Comment 2 Nate Graham 2020-07-11 04:42:48 UTC
*** Bug 422370 has been marked as a duplicate of this bug. ***
Comment 3 Nate Graham 2020-09-09 03:40:38 UTC
*** Bug 398117 has been marked as a duplicate of this bug. ***
Comment 4 Nate Graham 2020-09-09 03:40:42 UTC
*** Bug 418205 has been marked as a duplicate of this bug. ***
Comment 5 Nate Graham 2020-09-09 03:46:08 UTC
*** Bug 418442 has been marked as a duplicate of this bug. ***
Comment 6 Nate Graham 2020-09-09 03:47:55 UTC
I can confirm this issue on my machine.
Comment 7 Nate Graham 2020-09-23 15:21:53 UTC
I can also reproduce this when a large number of notifications get *deleted*. Consider the following:

1. Open Telegram and connect to a high-volume room (e.g. the KDE VDG room)
2. Focus a different room
3. Put the computer to sleep
4. Wake the computer up 12 hours or a day or two later

Telegram will now send hundreds of notifications, one for each unread message. This is annoying and can *sometimes* freeze the system.


If you then make the mistake of clicking on the room that sent the messages, Telegram will revoke all of the notifications at once (because they're no longer considered unread, presumably) , which will prompt the notifications on screen to go ballistic! They will all try to disappear at once, and will overlap one another and freeze the system 100% of the time (in my experience)
Comment 8 vindicator 2020-10-10 23:33:14 UTC
Version: 5.19.5-3
I've just experienced this myself for the (first? Maybe never before or for years.) time.
Except I only see 2 frozen notifications.
I attached the the plasmashell process and got a backtrace for it:
#0  0x00007f28ee0436a2 in pthread_cond_wait@@GLIBC_2.3.2 () at /usr/lib/libpthread.so.0
#1  0x00007f28eeb880d4 in QWaitCondition::wait(QMutex*, QDeadlineTimer) () at /usr/lib/libQt5Core.so.5
#2  0x00007f28f080f5d7 in  () at /usr/lib/libQt5Quick.so.5
#3  0x00007f28f0878bb7 in QQuickWindow::event(QEvent*) () at /usr/lib/libQt5Quick.so.5
#4  0x00007f28ef883752 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#5  0x00007f28eed67cda in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#6  0x00007f28ef12f319 in QPlatformWindow::windowEvent(QEvent*) () at /usr/lib/libQt5Gui.so.5
#7  0x00007f28ef88a437 in QApplication::notify(QObject*, QEvent*) () at /usr/lib/libQt5Widgets.so.5
#8  0x00007f28eed67cda in QCoreApplication::notifyInternal2(QObject*, QEvent*) () at /usr/lib/libQt5Core.so.5
#9  0x00007f28eedbfcc5 in QTimerInfoList::activateTimers() () at /usr/lib/libQt5Core.so.5
#10 0x00007f28eedc05aa in  () at /usr/lib/libQt5Core.so.5
#11 0x00007f28ed1e2bfc in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
#12 0x00007f28ed2341f9 in  () at /usr/lib/libglib-2.0.so.0
#13 0x00007f28ed1e1421 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#14 0x00007f28eedc0941 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /usr/lib/libQt5Core.so.5
#15 0x00007f28eed6665c in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#16 0x00007f28eed6eaf4 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#17 0x00005e570ab3bf5d in  ()
#18 0x00007f28ee734152 in __libc_start_main () at /usr/lib/libc.so.6
#19 0x00005e570ab3c19e in _start ()
In the meantime, I'll just --replace it.
Comment 9 vindicator 2020-10-10 23:37:03 UTC
... or maybe I won't --replace it (because it just doesn't want to), and I have to SIGTERM it.
Comment 10 Bug Janitor Service 2020-12-01 13:34:11 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/plasma-workspace/-/merge_requests/495
Comment 11 Kai Uwe Broulik 2021-01-11 21:58:32 UTC
Git commit d8e0071f1d735238feee5b181c30ab45cbc54803 by Kai Uwe Broulik.
Committed on 11/01/2021 at 19:06.
Pushed by broulik into branch 'master'.

[Notifications] Compress removal of notifications

When removing a notification, it is removed from the model, which will cause the
view to update and move up an older notification, if any. If you now delete a bunch
of notifications in quick succession we will create a dialog every time which then
gets deleted again, causing another notification to move up, etc causing high CPU
spikes and plasma freezes.

This patch compresses removing notifications and tries to announce consecuetive
ranges of notifications to be removed in one go.
FIXED-IN: 5.21.0

M  +71   -38   libnotificationmanager/abstractnotificationsmodel.cpp
M  +2    -0    libnotificationmanager/abstractnotificationsmodel.h
M  +8    -0    libnotificationmanager/abstractnotificationsmodel_p.h
M  +66   -1    libnotificationmanager/autotests/notifications_test.cpp
M  +1    -1    libnotificationmanager/notificationsmodel.h

Comment 12 Ben Cooksley 2021-01-12 02:25:57 UTC
Remove subscriber per abuse report
Comment 13 Nate Graham 2021-03-02 17:42:25 UTC
*** Bug 433775 has been marked as a duplicate of this bug. ***
Comment 14 Nate Graham 2021-04-09 02:43:58 UTC
*** Bug 435506 has been marked as a duplicate of this bug. ***