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List:       kde-devel
Subject:    NetworkManager and DBus issues [was: Re: DBUS issues with KDE 4 and Frameworks 5]
From:       Milian Wolff <mail () milianw ! de>
Date:       2015-01-21 16:27:35
Message-ID: 5065555.y1tJTx0pEP () milian-kdab2
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On Thursday 13 November 2014 17:54:21 Milian Wolff wrote:
> Hey all,
> 
> https://community.kde.org/Frameworks/Building says:
> > Warning: never start a KDE 4 application in this separate DBus session, it
> > would conflict with your running Plasma 4 desktop.
> 
> I just did that accidentally and now my whole system seems to be completely
> fubared. Most applications freeze sooner or later with a backtrace like
> this:
> 
> (gdb) bt
> #0  0x00007ffff3b6d5bd in poll () from /usr/lib/libc.so.6
> #1  0x00007fffefab2028 in ?? () from /usr/lib/libdbus-1.so.3
> #2  0x00007fffefab0ed8 in ?? () from /usr/lib/libdbus-1.so.3
> #3  0x00007fffefa9a474 in ?? () from /usr/lib/libdbus-1.so.3
> #4  0x00007fffefa9ae4d in ?? () from /usr/lib/libdbus-1.so.3
> #5  0x00007fffefa9b42a in dbus_connection_send_with_reply_and_block () from
> /usr/lib/libdbus-1.so.3
> #6  0x00007ffff4683e20 in ?? () from /usr/lib/libQtDBus.so.4
> #7  0x00007ffff4685dc2 in ?? () from /usr/lib/libQtDBus.so.4
> #8  0x00007ffff469166b in ?? () from /usr/lib/libQtDBus.so.4
> #9  0x00007ffff46917a5 in QDBusInterface::QDBusInterface(QString const&,
> QString const&, QString const&, QDBusConnection const&, QObject*) ()
>    from /usr/lib/libQtDBus.so.4
> #10 0x00007ffff73ec3d2 in ?? () from /usr/lib/libkio.so.5
> 
> After a very long timeout (30s?) the apps figure out something is wrong and
> continue to work as intended.
> 
> Can we somehow improve this situation? I find it very ugly that by
> accidentally executing a globally installed KDE4 installation in my KF5
> environment, I can completely screw up my "host" system.
> 
> Is there anything I should do differently maybe? How do other developers
> cope with this issue?

I'm hitting this issue again now. I have created a folder which contains 
symlinks to

$kf5-install-prefix/share/dbus-1
$kf5-install-prefix/share/kservicetypes5
$kf5-install-prefix/share/kservices5

I thought I got it working, but recently I see the deadlocks again. I'm not so 
sure whether its related to KF5 anymore though. I rather think its because I 
installed network manager to replace wicd. Indeed, I cannot reproduce the 
issue on a desktop machine that does not use NetworkManager, only on a laptop. 
And there, mostly after suspend/resume. Additionally, I see extreme 
performance drains in kded4 when I try to connect to a network with the kde4 
plasma network manager utility. Perf shows immense amount of CPU consumption 
in __pthread_mutex_lock and __pthread_mutex_unlock_usercnt below 
dbus_connection_send_with_replace_and_block (I'm missing debug symbols for 
kded4 and Qt4 - sorry).

Is this a known issue? On the web I found e.g. 
https://bbs.archlinux.org/viewtopic.php?id=163350 . Is there anything else I 
could do to debug this issue? Is there a dbus log or something that I could 
figure out what queries are done? Are there log files? It's pretty annoying to 
me, and I think I'll get rid of NetworkManager again to see if that really is 
the culprit.

Bye

-- 
Milian Wolff
mail@milianw.de
http://milianw.de

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