Hang using window switcher (alt-Tab)

[LJanardhan]

Hi everyone
 I am new to GNU/LINUX
 i use UBUNTU GUTSY v 7.10.
            From 3 days try to switch between programs my computer freezes. This happens when compiz-Fusion is running. But if i switch between programs when Compiz-Fusion is not running problem will not be there.
           Also i have noticed that the titlebar vanishes when I run Compiz-Fusion. And hhave to close the window from the panel only.
           Thanking you for giving me a chance to report this Bug.

[Pedro Villavicencio (pedro)]

Thanks for taking the time to report this bug and helping to make Ubuntu better. Could you please add your ~/.xsession-errors, /var/log/Xorg.0.log and the output of lspci -vvnn to your bug report as separate attachments? Thanks in advance.

[Pedro Villavicencio (pedro)]

We are closing this bug report because it lacks the information we need to investigate the problem, as described in the previous comments. Please reopen it if you can give us the missing information, and don't hesitate to submit bug reports in the future. To reopen the bug report you can click on the current status, under the Status column, and change the Status back to "New". Thanks again!.

[Neal McBurnett (nealmcb)]

I have also seen this problem, and been able to reproduce it at least twice after fiddling with the keys for a while. It seems to have something to do with pressing the space key and/or maybe the mouse or arrow keys or others while holding ctrl down and pressing tab.

My attempts to start up a replacement with compiz --replace didn't work, even though I tried to use the environment from the original one which I found in /proc, and I used the same command line arguments. Starting a metacity also didn't work.

Killing compiz from an ssh session allowed me to save some files and exit, but I wonder how I could have restarted a window manager.

It seems like having an option to restart compiz by killing it with sigusr1 or something like that would make this a lot easier to recover from.

Thanks for the tips on debugging - when I see this again I'll look at those files.

Changing status back to incomplete.

[Neal McBurnett (nealmcb)]

I forgot to add that I'm using a pretty fresh and up-to-date hardy install: 2.6.24-16-generic #1 SMP Thu Apr 10 12:47:45 UTC 2008 x86_64 GNU/Linux

[Pedro Villavicencio (pedro)]

Closing this bug report as no further information has been provided. Please feel free to reopen this bug if you can provide the information asked for. Thanks!.

[Thom Pischke (thom-pischke)]

Reopening as I am suffering from this bug consistently since upgrading to intrepid, and since it has already been confirmed by another user.

[Thom Pischke (thom-pischke)]

attaching requested info:

[Thom Pischke (thom-pischke)]

deleted .xsession-errors, rebooted and turned on compiz, then tried to duplicate this issue.

1. Started Firefox and Rhythmbox with both windows maximized
2. From Rhythmbox, pressed alt-tab. Success, able to flip back and forth between images of rhythmbox and firefox windows
3. Minimized all windows so desktop visible. Pressed alt-tab.

HANG. Everything frozen except mouse. Ctrl-Alt-Backspace unresponsive. All applets, menus, programs frozen. No life outside the mouse cursor. Hard reset of computer and reboot. This is what always happens. It happens at other times too, at least once a day, making compiz nearly unusable for me. Sometimes it seems to hang just 'cuz, when I'm doing nothing in particular except maybe changing a tab in firefox or activating some windows.

Good Luck!

~/.xsessions-errors file does not exists, I assume because no errors were written since I rebooted. That would mean the hard-hang doesn't result in an error being written.

[Thom Pischke (thom-pischke)]

See also:

bug #175744
bug #177488

[Thom Pischke (thom-pischke)]

Looked through the various Xorg.log files. Found this massively repeating error message at the end of one, This must be the problem:

[mi] EQ overflowing. The server is probably stuck in an infinite loop.
[mi] mieqEnequeue: out-of-order valuator event; dropping.
[mi] EQ overflowing. The server is probably stuck in an infinite loop.
[mi] mieqEnequeue: out-of-order valuator event; dropping.
[mi] EQ overflowing. The server is probably stuck in an infinite loop.
[mi] mieqEnequeue: out-of-order valuator event; dropping.

Attaching the file:

[Thom Pischke (thom-pischke)]

Possibly related: http://bugs.gentoo.org/show_bug.cgi?id=207106

[LJanardhan (janardhan-iyengar)]

Even after upgrading to Intrepid i face the same problem
Here is the Xorg.0.log
http://launchpadlibrarian.net/20561500/Xorg.0.log
lspci -vvnn
http://launchpadlibrarian.net/20561510/lspci%20-vvnn.txt

[Joel Goguen (jgoguen)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. You reported this bug a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue for you. I'm not able to Can you try with the latest Ubuntu release? Thanks in advance.

[LJanardhan (janardhan-iyengar)]

First of all I would like to thank everyone for giving me a chance to report
a bug.
Well this problem isn't there in Jaunty. So this is not a issue now.

On Tue, May 5, 2009 at 2:29 AM, Joel Goguen <email address hidden> wrote:

> Thank you for taking the time to report this bug and helping to make
> Ubuntu better. You reported this bug a while ago and there hasn't been
> any activity in it recently. We were wondering if this is still an issue
> for you. I'm not able to Can you try with the latest Ubuntu release?
> Thanks in advance.
>
> ** Changed in: compiz (Ubuntu)
> Status: Confirmed => Incomplete
>
> --
> system hangs on pressing <Alt><Tab> while using Compiz-Fusion
> https://bugs.launchpad.net/bugs/161000
> You received this bug notification because you are a direct subscriber
> of the bug.
>

--
Lakshmi Janardhan

[Joel Goguen (jgoguen)]

This bug report is being closed due to your last comment regarding this being fixed with an update. For future reference you can manage the status of your own bugs by clicking on the current status in the yellow line and then choosing a new status in the revealed drop down box. You can learn more about bug statuses at https://wiki.ubuntu.com/Bugs/Status . Thank you again for taking the time to report this bug and helping to make Ubuntu better. Please submit any future bugs you may find.

[Thom Pischke (thom-pischke)]

This is still an issue in jaunty. Happens a bit less frequently, but still happens. I never use Alt-Tab, since it usually kills my computer dead.

[Joel Goguen (jgoguen)]

Hi Thom,

This bug is being reopened because of your last comment regarding this still being an issue with Jaunty. I am still unable to reproduce this using Jaunty with binary nVidia drivers. Could you please reproduce this issue and post new output from lspci, a new X server configuration file (/etc/X11/xorg.conf) and a new X server log file (/var/log/Xorg.0.log) to the bug report as individual uncompressed file attachments using the "Attachment:" box below? Could you please also try to run without any /etc/X11/xorg.conf (just rename it to something other than /etc/X11/xorg.conf) and reboot to let Xorg autodetect your display and video card? Please try again to reproduce this issue with that setup, and attach the /var/log/Xorg.0.log from this attempt.

Thanks in advance!

[Joel Goguen (jgoguen)]

Also, if anyone on this bug is using a nVidia or ATi card, with either binary or free drivers, and can reproduce this issue, could you please follow the above directions and let us know what driver you're using?

[Thom Pischke (thom-pischke)]

I have the intel x3100, will test when I have a chance...

[Falebuntu (faleloncio)]

Hi to everybody

Maybe this is not proper forum, but I have same problem related here, but a similar scenary: Most times when I use <Alt><Tab> to switch windows, on releasing <Alt> my Linux hangs.
Scenary: OpenSuse 11.1 + Gnome + Nvidia Gforce 9800 GT + Compiz

Maybe the problem is Gnome + Compiz related, not debian or redhat operating systems.

Thank you

[Travis Watkins (amaranth)]

Can someone who was having this problem see if it still occurs with karmic? If you don't want to upgrade you can wait until alpha 6 comes out here in a couple days and try it from the LiveCD. There was a bug that I think may be the same as this one that was fixed with a kernel change.

[Varghese Mathew (vmathew)]

I have the latest updates as of two days ago on Jaunty Jackalope.. And this issue is hit frequently..
So much so that, I have disabled all types of "Alt-Tab" window switchers including the basic one..

My graphics card is the intel 965 board's default card.. (dell vostro 1310 laptop).. It's blacklisted on jaunty and I
had to disable blacklisting.. but then _everything_ else on compiz works except this annoying bug exists..
The system just freezes on alt-tab.. (the shifter pop up / ring display comes before it freezes..) and not even
ctrl alt backspace / delete works... can't go to a terminal with ctrl alt f1.. hard reset is the only option..

it has happened on this box almost everytime when I've had quite a few windows open (like maybe 4-5 on each face
of a cube of four faces..)

I'd recommend making this bug a high priority, looks like something's seriously bugged up in the switcher code..

[Varghese Mathew (vmathew)]

Further searching points me to this page http://www.ivankristianto.com/2009/03/tips-alt-tab-make-ubuntu-freezes/
Which claims that unchecking reflection will remove this issue.. Wonder if it's some race condition between reflection and shifters..

[El Samuels (wesamuels)]

I consistently obtain similar results:
- Can use Meta+Tab fine to cycle through applications, but not Alt+Tab
- Using Alt-Tab causes some applications (including Nautilus, FireFox, and LibreOffice, but not Krusader) to no longer response to mouse or keyboard input
- Shutting down and restarting the given application restores its responsiveness

System info (can provide more if needed; sorry I'm not sure what all I should report, I'm just kinda going with what others did):
Ubuntu 11.04
Kernel Linux 2.6.38-10-generic-pae
GNOME 2.32.1
Compiz
ATI graphics card

[joe (mjoachimiak)]

Same problem for me.
I don't know if it matters but I reverted to original Alt+Tab behaviour using this hint: http://askubuntu.com/questions/68151/revert-alt-tab-behavior-changed-in-11-10

The problems started after that.

Now I reverted back to gnome and everything is fine.

IMHO unity at the current state should go back to the lab tests.