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List: kde-panel-devel
Subject: Re: Review Request 121710: Avoid risk of starting two kscreen_launchers at the same having race cond
From: Lukáš Tinkl <lukas () kde ! org>
Date: 2014-12-29 20:34:30
Message-ID: 20141229203430.18352.71671 () probe ! kde ! org
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> On Pro. 29, 2014, 2:55 dop., Lukáš Tinkl wrote:
> > Unfortunataly it doesn't fix it here, plasmashell starts with a blank screen. \
> > kquitapp5 plasmashell && plasmashell brings it back
>
> Bhushan Shah wrote:
> Works for me.. :S which XRandr version you have?
>
> David Edmundson wrote:
> That's depressing to hear. I need some help on this; logs, traces, something as I \
> can't reproduce here and this bug is super duper critical.
> Do you agree this change still makes sense though? Even if there is another problem \
> it will be easier if there's one potential bug less.
> Raymond Wooninck wrote:
> Unfortunately I seem to have hit a worse situation. kquitapp5 plasmashell does not \
> work in my case as it just fails. Killing plasmashell and then starting it just \
> delivers the same situation, a black screen with plasmashell running in the \
> background and that is it. Starting plasmashell shows the \
> following output:
> kscreen: launcherDataAvailable: "org.kde.KScreen.Backend.XRandR"
> kscreen: Launcher finished with exit code 1 , status 0
> kscreen: Service for requested backend already running
>
> And yes I have a kscreen_backend_launcher process running, which is started by \
> kded5. When I try to kill this one, kded5 is automatically restarting it.
> To be honest this patch makes things worse as that plasmashell is not starting at \
> all.
> Raymond Wooninck wrote:
> Just forgot:
> raymond@HQVMT44011:~% xrandr --version
> xrandr program version 1.4.3
> Server reports RandR version 1.4
>
> Bhushan Shah wrote:
> > kscreen: launcherDataAvailable: "org.kde.KScreen.Backend.XRandR"
> > kscreen: Launcher finished with exit code 1 , status 0
> > kscreen: Service for requested backend already running
>
> I had same output but with this patch I am not getting that.. and plasmashell works \
> for me fine.
> Raymond Wooninck wrote:
> Ok. I dived a little deeper into the issues that I got (as that reverting the patch \
> didn't help) and it appeared that I had to clean my config files. I deleted all the \
> "plasma*" files/directories from .config and after this I was able to start \
> plasmashell again. A new problem arose with the kcache files for the plasma theme, \
> which caused plasma freezes. Deleting those made my installation happy and now I \
> can boot normally and plasmashell is starting.
> Lukas, you might want to give this patch a try with a clean user, to see if it \
> works. However it seems not to resolve the issue completely as that another person \
> indicated that with a new user, he now gets the old issue despite that with his \
> normal user everything works fine.
No change, even with a new user. KScreen also routinely forgets my settings and sets \
the external monitor as a clone (although my setup is an extension to the right side) \
and unsets the primary display to be empty.
- Lukáš
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/121710/#review72655
-----------------------------------------------------------
On Pro. 28, 2014, 11:33 dop., David Edmundson wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/121710/
> -----------------------------------------------------------
>
> (Updated Pro. 28, 2014, 11:33 dop.)
>
>
> Review request for Plasma, Solid and Daniel Vrátil.
>
>
> Repository: libkscreen
>
>
> Description
> -------
>
> Avoid risk of starting two kscreen_launchers at the same having a race condition.
>
> There were three possible bugs:
> CheckIsAlreadyRunning tried to register a service and check if it worked.
> This could clash with another process checking at the same time. Causing them both \
> to fail saying another is running Similarly, a daemon doing actual registering \
> could clash with another daemon just checking if the name is free, and then it \
> would fail saying we can't init()
> There was also a risk that two launchers pass the check that nothing is running, \
> then both try to activate a session. DBus server handles this fine and one will \
> gracefully fail. Without this patch the second launcher would just die without \
> returning the path of the service that was activated causing the relevant app to do \
> nothing.
>
> --
>
> IMHO, you'd be better off having a fixed service name and using DBus activation for \
> exactly these reasons. You could put the different backends at different object \
> paths, and have a method on the root object that says which object path to use \
> rather than using the stdout of a launcher. That's a discussion for another day \
> though.
>
> Diffs
> -----
>
> src/backendlauncher/backendloader.cpp e7da8cd
> src/backendlauncher/main.cpp f8bf323
>
> Diff: https://git.reviewboard.kde.org/r/121710/diff/
>
>
> Testing
> -------
>
> Send it to bshah. Plasmashell started for him. Previously it didn't.
>
>
> Thanks,
>
> David Edmundson
>
>
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This is an automatically generated e-mail. To reply, visit:
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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On prosinec 29th, 2014, 2:55 dop. CET, <b>Lukáš \
Tinkl</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;"> <pre style="white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Unfortunataly it doesn't fix it here, plasmashell \
starts with a blank screen. kquitapp5 plasmashell && plasmashell brings it \
back</p></pre> </blockquote>
<p>On prosinec 29th, 2014, 3:42 dop. CET, <b>Bhushan Shah</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Works \
for me.. :S which XRandr version you have?</p></pre> </blockquote>
<p>On prosinec 29th, 2014, 11:54 dop. CET, <b>David Edmundson</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">That's depressing to hear. I need some help on this; logs, traces, \
something as I can't reproduce here and this bug is super duper critical.</p> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Do you agree this change still makes sense though? Even if there is another \
problem it will be easier if there's one potential bug less.</p></pre> </blockquote>
<p>On prosinec 29th, 2014, 5:05 odp. CET, <b>Raymond Wooninck</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Unfortunately I seem to have hit a worse situation. kquitapp5 plasmashell \
does not work in my case as it just fails. Killing plasmashell and then starting it \
just delivers the same situation, a black screen with plasmashell running in the \
background and that is it. Starting plasmashell shows the following \
output:
kscreen: launcherDataAvailable: "org.kde.KScreen.Backend.XRandR"
kscreen: Launcher finished with exit code 1 , status 0
kscreen: Service for requested backend already running</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">And yes I have a kscreen_backend_launcher process \
running, which is started by kded5. When I try to kill this one, kded5 is \
automatically restarting it. </p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">To be honest this patch \
makes things worse as that plasmashell is not starting at all.</p></pre> \
</blockquote>
<p>On prosinec 29th, 2014, 5:05 odp. CET, <b>Raymond Wooninck</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Just \
forgot: raymond@HQVMT44011:~% xrandr --version
xrandr program version 1.4.3
Server reports RandR version 1.4</p></pre>
</blockquote>
<p>On prosinec 29th, 2014, 5:40 odp. CET, <b>Bhushan Shah</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><blockquote \
style="text-rendering: inherit;padding: 0 0 0 1em;border-left: 1px solid \
#bbb;white-space: normal;margin: 0 0 0 0.5em;line-height: inherit;"> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">kscreen: launcherDataAvailable: \
"org.kde.KScreen.Backend.XRandR"
kscreen: Launcher finished with exit code 1 , status 0
kscreen: Service for requested backend already running</p>
</blockquote>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">I had same output but with this patch I am not getting \
that.. and plasmashell works for me fine.</p></pre> </blockquote>
<p>On prosinec 29th, 2014, 9:07 odp. CET, <b>Raymond Wooninck</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Ok. I \
dived a little deeper into the issues that I got (as that reverting the patch didn't \
help) and it appeared that I had to clean my config files. I deleted all the \
"plasma*" files/directories from .config and after this I was able to start \
plasmashell again. A new problem arose with the kcache files for the plasma theme, \
which caused plasma freezes. Deleting those made my installation happy and now I can \
boot normally and plasmashell is starting.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">Lukas, you might want \
to give this patch a try with a clean user, to see if it works. However it seems not \
to resolve the issue completely as that another person indicated that with a new \
user, he now gets the old issue despite that with his normal user everything works \
fine.</p></pre> </blockquote>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">No \
change, even with a new user. KScreen also routinely forgets my settings and sets the \
external monitor as a clone (although my setup is an extension to the right side) and \
unsets the primary display to be empty.</p></pre> <br />
<p>- Lukáš</p>
<br />
<p>On prosinec 28th, 2014, 11:33 dop. CET, David Edmundson wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
1px #888a85 solid; border-radius: 6px; -moz-border-radius: 6px; \
-webkit-border-radius: 6px;"> <tr>
<td>
<div>Review request for Plasma, Solid and Daniel Vrátil.</div>
<div>By David Edmundson.</div>
<p style="color: grey;"><i>Updated Pro. 28, 2014, 11:33 dop.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
libkscreen
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Avoid risk of starting two kscreen_launchers at the \
same having a race condition.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">There were three \
possible bugs: CheckIsAlreadyRunning tried to register a service and check if it \
worked. This could clash with another process checking at the same time. Causing them \
both to fail saying another is running Similarly, a daemon doing actual registering \
could clash with another daemon just checking if the name is free, and then it would \
fail saying we can't init()</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">There was also a risk that two \
launchers pass the check that nothing is running, then both try to activate a \
session. DBus server handles this fine and one will gracefully fail. Without this \
patch the second launcher would just die without returning the path of the service \
that was activated causing the relevant app to do nothing.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">--</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">IMHO, you'd be better off having a fixed service name \
and using DBus activation for exactly these reasons. You could put the different \
backends at different object paths, and have a method on the root object that says \
which object path to use rather than using the stdout of a launcher. That's a \
discussion for another day though.</p></pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Send it to bshah. Plasmashell started for him. \
Previously it didn't.</p></pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>src/backendlauncher/backendloader.cpp <span style="color: \
grey">(e7da8cd)</span></li>
<li>src/backendlauncher/main.cpp <span style="color: grey">(f8bf323)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/121710/diff/" style="margin-left: \
3em;">View Diff</a></p>
</td>
</tr>
</table>
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