application not responding (ANR) handling

[Harald Sitter]

Ciao!

A while ago I was thinking about ANR handling but then forgot about it
again, some malfunction reminded me of it again so I thought I should
write down some musings. Maybe y'all have some input as well.

Right now we don't really know when our applications deadlock because
kwin somewhat gracefully kills the process when it detects no answer
to window actions, leaving no trace of the malfunction for debugging.
Even outside that feature it's exceptionally hard for a user to
generate an ANR report because the user either needs to SEGV the app
manually (at which point kcrash and drkonqi kick in), or attach a
debugger (requiring basically developer-level knowledge). All in all a
garbage situation.

It's actually a bit tricky to solve because currently it seems neither
POSIX nor Linux have a concept of ANR defects so we need some custom
metadata on top.

Here's my thinking...

- The way kwin does the killing is in a helper binary that more or
less simply calls kill() on the stuck pid
- The kill helper could write some trivial metadata to
.cache/kwin/anr/$exe.$bootid.$pid.$time_at_time_of_crash.json (the
name format is the one used by coredumpd as well FWIW)
- It could then send ABRT instead of KILL as first signal
- It should probably also make sure the pid actually shoved off in
some timeout or else send KILL
- KCrash kicks in and does the handover dance with drkonqi
- DrKonqi can check for the ANR metadata and then mark the report ANR
for sentry and bugzilla

3rd party software would still get ABRT and if they have a crash
handler they'll be able to handle it, it will look like a random ABRT
at a glance but they'll have at least the possibility of noticing that
something is deadlocking in their software. I don't think there's a
better solution for them right now, seeing as we have no platform way
to tell them this ABRT was ANR. Of course if they are running outside
a sandbox they are free to also pick up the kwin ANR metadata.

When no crash handlers of any sort are installed ABRT will by default
cause a core dump, which then ideally goes into a crash handler daemon
like coredumpd. In fact, with coredumpd the user is then able to
excavate such deadlock traces via drkonqi's crashed process viewer.
Improving the debugging UX of deadlocks in general.

Since systemd also sends ABRT when a service watchdog barks this also
allows us to notice daemon deadlocks on systems where drkonqi covers
all software (e.g. plasma-mobile).

Any further thoughts on this?

HS

"Logout Screen" only shows shutdown when pressing the power button

[Michael Reeves]

Just noticed I am only getting shutdown as an option when pressing the
power button. This is not acceptable any more then just having skip
directly  to shutdown. I choose to be presented with the log out dialog
because I want a choose of actions not a timer on the shutdown or else.
This is likely some sort of configuration change that I am not aware of.

Re: "Logout Screen" only shows shutdown when pressing the power button

[Nate Graham]

This was an intentional change in Plasma 6.1: now, if you choose shut 
down, restart, or log out, you're taken to a confirmation screen showing 
only the thing you asked for plus a cancel button, so it's more of a 
confirmation screen. If instead you'd actually like to see all options, 
you'll want to use the "show logout screen" action/shortcut/button etc. 
instead.


Nate


On 7/14/24 5:21 PM, Michael Reeves wrote:
Just noticed I am only getting shutdown as an option when pressing the 
power button. This is not acceptable any more then just having skip 
directly  to shutdown. I choose to be presented with the log out dialog 
because I want a choose of actions not a timer on the shutdown or else. 
This is likely some sort of configuration change that I am not aware of.

Re: "Logout Screen" only shows shutdown when pressing the power button

[Michael Reeves]

That's want i have selected in "Energy Saver" 6.1 ignores this setting and
treats as a shutdown with confirmation.

On Sun, Jul 14, 2024 at 5:24 PM Nate Graham  wrote:

> This was an intentional change in Plasma 6.1: now, if you choose shut
> down, restart, or log out, you're taken to a confirmation screen showing
> only the thing you asked for plus a cancel button, so it's more of a
> confirmation screen. If instead you'd actually like to see all options,
> you'll want to use the "show logout screen" action/shortcut/button etc.
> instead.
>
> Nate
>
>
> On 7/14/24 5:21 PM, Michael Reeves wrote:
> > Just noticed I am only getting shutdown as an option when pressing the
> > power button. This is not acceptable any more then just having skip
> > directly  to shutdown. I choose to be presented with the log out dialog
> > because I want a choose of actions not a timer on the shutdown or else.
> > This is likely some sort of configuration change that I am not aware of.
>

Re: "Logout Screen" only shows shutdown when pressing the power button

[Nate Graham]

That's not what's supposed to be happening, and it's working for me: if 
I select "Show logout screen" for the "when power button pressed" 
combobox, I see the screen with all options when I press the power button.


Make sure you have this selected for all power states if your device has 
a battery.


If that's not working for you, it sounds like there's a bug, so I would 
recommend opening a bu report about it.


Nate




On 7/14/24 6:11 PM, Michael Reeves wrote:
That's want i have selected in "Energy Saver" 6.1 ignores this setting 
and treats as a shutdown with confirmation.


On Sun, Jul 14, 2024 at 5:24 PM Nate Graham > wrote:


This was an intentional change in Plasma 6.1: now, if you choose shut
down, restart, or log out, you're taken to a confirmation screen
showing
only the thing you asked for plus a cancel button, so it's more of a
confirmation screen. If instead you'd actually like to see all options,
you'll want to use the "show logout screen" action/shortcut/button etc.
instead.

Nate


On 7/14/24 5:21 PM, Michael Reeves wrote:
 > Just noticed I am only getting shutdown as an option when
pressing the
 > power button. This is not acceptable any more then just having skip
 > directly  to shutdown. I choose to be presented with the log out
dialog
 > because I want a choose of actions not a timer on the shutdown or
else.
 > This is likely some sort of configuration change that I am not
aware of.

Re: "Logout Screen" only shows shutdown when pressing the power button

[Kai Uwe Broulik]

Hi,

I guess that’s the same issue I had where I had a leftover “default 
logout option” in settings, so the “Leave” screen defaulted to that 
option (e.g. only Shutdown) without the other options.


Cheers
Kai uwe

Am 15.07.24 um 00:22 schrieb Nate Graham:
That's not what's supposed to be happening, and it's working for me: if 
I select "Show logout screen" for the "when power button pressed" 
combobox, I see the screen with all options when I press the power button.


Make sure you have this selected for all power states if your device has 
a battery.


If that's not working for you, it sounds like there's a bug, so I would 
recommend opening a bu report about it.


Nate