Bug 439805

Summary:	Move individual tabbed/windowed processes into their own systemd scope
Product:	[Applications] konsole	Reporter:	Chris Murphy <bugzilla>
Component:	general	Assignee:	Konsole Bugs <konsole-bugs-null>
Status:	RESOLVED FIXED
Severity:	wishlist	CC:	4wy78uwh, a.samirh78, benjamin, kde, kde, nate, r2b2x3+kdebug, stalkerg, tcanabrava
Priority:	NOR
Version First Reported In:	master
Target Milestone:	---
Platform:	Other
OS:	Linux
See Also:	https://bugs.kde.org/show_bug.cgi?id=480884
Latest Commit:	https://invent.kde.org/utilities/konsole/-/commit/1525ee3b5ea58b09d551f41b0bd6f0f91589e070	Version Fixed/Implemented In:	23.12
Sentry Crash Report:
Attachments:	attachment-419896-0.html

Description Chris Murphy 2021-07-13 14:48:04 UTC

SUMMARY

systemd-oomd only tracks and kills at the cgroups level. If a child process in Konsole consumes too many resources, the entire Konsole cgroup is subject to being killed by oomd including all of its child processes. This is inconvenient.


See downstream bugs:
https://bugzilla.redhat.com/show_bug.cgi?id=1977610



SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 34 KDE, systemd 248 

ADDITIONAL INFORMATION


On Fedora with GNOME, vte moves each process into its own scope, and thus its own cgroup assignment. The code is here: https://gitlab.gnome.org/GNOME/vte/-/blob/master/src/systemd.cc

I think the solution is Konsole needs a similar enhancement, that way each tab's process(es) is effectively tracked in its own cgroup, and only that tab is subject to being killed off by oomd.

Comment 1 tcanabrava 2021-07-13 15:08:33 UTC

This is quite nice. thanks for pointing that out.

Comment 2 tcanabrava 2021-07-13 15:35:05 UTC

Is there any easy way to test this?
I'v tested tail /dev/zero but that just eat my whole memory and I couldn't even move the mouse.

Comment 3 Benjamin Berg 2021-07-13 15:46:08 UTC

The easiest way to verify cgroup creation/layout is to run
  cat /proc/self/cgroup
in a terminal tab.

systemd-oomd will always kill an entire cgroup. So if all the child processes are in the same cgroup then they will all be killed together.

Comment 4 Nate Graham 2021-08-03 02:42:08 UTC

Good idea!

Comment 5 Bug Janitor Service 2023-06-24 14:31:53 UTC

A possibly relevant merge request was started @ https://invent.kde.org/utilities/konsole/-/merge_requests/866

Comment 6 Kurt Hindenburg 2023-08-28 23:59:20 UTC

Git commit 1525ee3b5ea58b09d551f41b0bd6f0f91589e070 by Kurt Hindenburg, on behalf of Theodore Wang.
Committed on 29/08/2023 at 01:59.
Pushed by hindenburg into branch 'master'.

Create separate cgroups for processes of each tab

Currently, all the processes created by the application are housed
within the application's cgroup without any futher categorisation.
This causes the entire application to be killed if a process in the
aforementioned cgroup triggers an OOM event.

To prevent the entire application from being killed, a new child cgroup
is created for each new tab. Child cgroups for individual tabs are
named according to this template "tab([session pid for the tab]).scope".
"Background" processes (e.g. such as the main process for running
konsole) are stored in the child cgroup "main.scope".
This restricts the OOM event to only killing the tab which contains
the offending process.

To prevent the entire application from being killed, a new child cgroup is created for each new tab.
Child cgroups for individual tabs are named according to this template "tab([session pid for the tab]).scope".
"Background" processes (e.g. such as the main process for running konsole) are stored in the child cgroup "main.scope".
This restricts the OOM event to only killing the tab which contains the offending process.

M +2 -0 src/CMakeLists.txt
M +7 -0 src/MainWindow.cpp
M +226 -3 src/ProcessInfo.cpp
M +3 -1 src/ProcessInfo.h
M +1 -1 src/session/Session.cpp
A +18 -0 src/settings/MemorySettings.cpp *
A +18 -0 src/settings/MemorySettings.h *
A +62 -0 src/settings/MemorySettings.ui
M +10 -0 src/settings/konsole.kcfg

The files marked with a * at the end have a non valid license. Please read: https://community.kde.org/Policies/Licensing_Policy and use the headers which are listed at that page.

https://invent.kde.org/utilities/konsole/-/commit/1525ee3b5ea58b09d551f41b0bd6f0f91589e070

Comment 7 Kurt Hindenburg 2023-08-28 23:59:28 UTC

Git commit 1525ee3b5ea58b09d551f41b0bd6f0f91589e070 by Kurt Hindenburg, on behalf of Theodore Wang.
Committed on 29/08/2023 at 01:59.
Pushed by hindenburg into branch 'master'.

Create separate cgroups for processes of each tab

To prevent the entire application from being killed, a new child cgroup is created for each new tab.
Child cgroups for individual tabs are named according to this template "tab([session pid for the tab]).scope".
"Background" processes (e.g. such as the main process for running konsole) are stored in the child cgroup "main.scope".
This restricts the OOM event to only killing the tab which contains the offending process.

The files marked with a * at the end have a non valid license. Please read: https://community.kde.org/Policies/Licensing_Policy and use the headers which are listed at that page.

https://invent.kde.org/utilities/konsole/-/commit/1525ee3b5ea58b09d551f41b0bd6f0f91589e070

Comment 8 Yury Zhuravlev 2023-09-03 03:56:41 UTC

What about OpenRC users? Is it make sense to use a separate cgroup for each tab on OpenRC?

Comment 9 ninjalj 2023-09-04 11:21:42 UTC

Created attachment 161399 [details]
attachment-419896-0.html

On OpenRC, each tab already gets a new cgroup via the autocgroup feature
provided by the kernel since 2.6.38.

AFAIK, SystemD wants more visibility, which us why it wants processes to
use its cgroup management API, so that then it can manage those cgroups in
a more personalized way.

On Sunday, September 3, 2023, Yury Zhuravlev <bugzilla_noreply@kde.org>
wrote:

> https://bugs.kde.org/show_bug.cgi?id=439805
>
> Yury Zhuravlev <stalkerg@gmail.com> changed:
>
>            What    |Removed                     |Added
> ------------------------------------------------------------
> ----------------
>                  CC|                            |stalkerg@gmail.com
>
> --- Comment #8 from Yury Zhuravlev <stalkerg@gmail.com> ---
> What about OpenRC users? Is it make sense to use a separate cgroup for
> each tab
> on OpenRC?
>
> --
> You are receiving this mail because:
> You are the assignee for the bug.

Comment 10 kb1000 2024-11-03 18:30:33 UTC

I believe the change/fix did not go far enough.
IMO, it should offer creating systemd scopes/cgroups without additional memory restrictions, and further should default to doing so.
I can't think of a scenario where you wouldn't want oomd to treat tabs separately from Konsole, so that would be a sane default.
I'm also noticing that unlike the linked GNOME implementation, Konsole appears to be creating a single systemd scope and manages sub-cgroups by itself - does that have any disadvantages? At least using .scope in the name of those sub-cgroups seems somewhat misleading, since they are *not* systemd scopes.