Bug 314803

Poosibly related to https://git.reviewboard.kde.org/r/108223/

I'm suffering from the same problem, pressing vol-up or vol-down will eventually cause KMix to hang and consume 100% CPU usage, it will hang for 30sec-2mins then carry out the backlog of adjustments I sent after it begun to hang.

Like illumilore, this seems to have only started since upgrading to 4.10.

After a short discussion, I think it is NOT related to https://git.reviewboard.kde.org/r/108223/. It sounds again much more like a DBUS communication "deadlock" on synchronous DBUS calls.
Hmm, does Pulseaudio synchronous DBUS calls? The described "hanf for 30s" is very close to Qt's default timeout of 25 seconds [1]. 

[1] https://bugreports.qt-project.org/browse/QTBUG-14485

I wonder whether it is related to PulseAudio. Please try KMix without PulseAudio?

# Disable PulseAudio in KMix:
    killall kmix; sleep 2;
    kwriteconfig -file kmixrc -group Global -key Backends -type string ALSA,MPRIS2 ;
    sleep 1 ; kmix

Try and please report back.

# Back to default behavior:
    killall kmix; sleep 2;
    kwriteconfig -file kmixrc -group Global -key Backends -type string "" ;
    sleep 1 ; kmix

Hi Christian,

I tried the fix you suggested and it seems to work. :) Changing the kmix backend to ALSA has removed all lag and random freezes from the OSD when adjusting the volume via the media keys.

Thanks for the feedback, John.

Not sure how to progress, though. Problem is similar to hanging Tabs in Firfox (One call to block them all). I cannot make PA calls non-blocking. Only possibly, theoretically the PA backend communication could - eventually -  run in its own thread, given that its own app-loop allows for it, and there is proper concurrency in Qt. All in all it sounds highly complex, possibly impossible and like nothing I can handle myself in a reasonable time frame.

It seems to be an update related configuration issue.
http://qdosmsq.dunbar-it.co.uk/blog/2011/11/does-your-volume-control-freeze-on-kde/
This solved the problem for me, without having to disable pulseaudio.  Christian Esken's solution may have just rewritten relevant parts of the config and made it work again. Try to re-enable pulsaudio and see if it still works.

(In reply to comment #7)
> It seems to be an update related configuration issue.
> http://qdosmsq.dunbar-it.co.uk/blog/2011/11/does-your-volume-control-freeze-
> on-kde/
> This solved the problem for me, without having to disable pulseaudio. 
> Christian Esken's solution may have just rewritten relevant parts of the
> config and made it work again. Try to re-enable pulsaudio and see if it
> still works.

Revoking what I said earlier. It works after booting, but I'm having the problem again after using my computer for a couple of hours.

*** Bug 317087 has been marked as a duplicate of this bug. ***

Affects me too.  I had to stop using kmix and create custom shortcuts that run amixer commands to change the volume, and I'm using veromix or pasystray when I need more control.

(In reply to comment #7)
> It seems to be an update related configuration issue.
> http://qdosmsq.dunbar-it.co.uk/blog/2011/11/does-your-volume-control-freeze-
> on-kde/
> This solved the problem for me, without having to disable pulseaudio. 
> Christian Esken's solution may have just rewritten relevant parts of the
> config and made it work again. Try to re-enable pulsaudio and see if it
> still works.

Thanks. It's helped me.

*** This bug has been confirmed by popular vote. ***

I am experiencing this too.  openSUSE 12.3, KDE 4.10.3.  Is a fix forthcoming?
I also tried the changes suggested by Christian Esken and it seems to have - for now - resolved the issue.

*** Bug 319787 has been marked as a duplicate of this bug. ***

Jon, did you read comment 11? Does it fix the problem for you? If not, then try what is written in  comment 4. Please report back once you have tested.

If you can provide the information requested in comment #15, please add it.

I had same freezing issue occasionaly.

Inspired by comment #7 I delete all kmix config files like this:
find ~/.kde4 -iname \*kmix\* -exec rm -r \{\} \;
and had no freezes since, hope it helps somebody

This issue remains unresolved.

This issue is now resolved with KDE 4.11.

Thanks for the update. Please reopen, if you see the bug with KDE 4.11.x or later again.

So to get rid of this bug I need to upgrade the OS. And every time I install KDE something is broken and needs to be "fixed" by upgrading to the next version. Will this ever end?

Is it really that difficult to patch a bug in the release where the bug is found?

And is writing a GUI for a mixer such a rocket science that bugs like this happen every once in a while (https://bugs.kde.org/show_bug.cgi?id=288675)?

>So to get rid of this bug I need to upgrade the OS. 
No. You can use any KMix version with your current KDE version. if your your Linux distribution ships them. Good distributions do.

> And is writing a GUI for a mixer such a rocket science
Yes. If you are really so smart, then do it yourself. And make sure you support 50 distributions, each for the last 10 versions, and 10 sound serves. And don't forget IRIX and Solaris support!

> No. You can use any KMix version with your current KDE version. if your your Linux distribution ships them. Good distributions do.

Really? Can you name at least one which allows me to use KDE 4.10 apart from kmix which would be taken from 4.11?

> Yes. If you are really so smart, then do it yourself. And make sure you support 50 distributions, each for the last 10 versions, and 10 sound serves. And don't forget IRIX and Solaris support!

Can you find at least one distribution of, say, Linux where KDE just works? No. And it is a very sorry situation. With every passing year Linux is becoming less useful as a desktop OS.