gnome shell freezes due to GC deadlock. intermittent

[shinyblue]

Occasionally, gnome shell locks up right after lightdm login. The mouse moves, but nothing responds to clicks. Keyboard is ignored.

I've found a work-around suitable for technical people only, which is to Ctrl-Alt-F1, log in, and type pkill -HUP gnome-shell, then log out and go back with Alt-F7.

At the command prompt, I observed 2 zombie lightdm processes. Not sure if related. Figured it was a gnome bug because restarting gnome-shell fixes it.

Having now rolled gnome-shell desktops out in my business to non-technical users, this is a serious bug: most of them have to do a hard reset.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gnome-shell 3.4.1-0ubuntu2
ProcVersionSignature: Ubuntu 3.2.0-30.48-generic 3.2.27
Uname: Linux 3.2.0-30-generic x86_64
ApportVersion: 2.0.1-0ubuntu13
Architecture: amd64
Date: Tue Oct 2 09:23:27 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Tim Lunn (darkxst)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It would be helpful if you can attach the following logs (after reproducing the crash).

'~/.xsession-errors'
'/var/log/Xorg.0.log'
'/var/log/syslog'

[Marcin (wor18)]

I have the same problem. (requested logs in the attachment)

[Tim Lunn (darkxst)]

There is nothing really in those logs. It would be useful if you can get a backtrace while gnome-shell is frozen.

https://live.gnome.org/GnomeShell/Debugging

Also make sure you install debug symbols
https://wiki.ubuntu.com/DebuggingProgramCrash#Debug_Symbol_Packages

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Noe (noecordmart)]

I have the same problem in two computers. Both Ubuntu 12.04 amd64.

[Tim Lunn (darkxst)]

Noe, we really need a backtrace on this to see what is going on, however I can't reproduce the issue here. So if you can follow the links in my previous post and get a backtrace while the shell is frozen and upload them here, I will look into it.

[Noe (noecordmart)]

Today it happened again. So I followed the instructions above and here it's the backtrace. Hope it helps.

[Tim Lunn (darkxst)]

Thanks for the logs, however you need to install debug symbols for the trace to be useful. (see the second link in comment #4).

atleast make sure you have installed debug symbols for mutter, gnome-shell, libmozjs, libnspr.

Also the output from 'call gjs_dumpstack' actually goes to gnome-shell stdout, not the gdb session

[Noe (noecordmart)]

I have just installed the debug symbols. So next time I will be able to send you useful data.

How can I capture the output from 'call gjs_dumpstack' ?

[Tim Lunn (darkxst)]

It will probably end up in '~/.xsession-errors'

[Noe (noecordmart)]

Here are the trace files.

I have installed the debug symbols indicated in #9, but in screenlog.0 the are several "no debug symbols found" messages, should I install debug symbols for all of those libraries?

[Tim Lunn (darkxst)]

Noe, Yes you need to get the symbols for libmozjs185 (these should be available on ddebs)

[Noe (noecordmart)]

Today it happend again. Here are the trace files.

[Tim Lunn (darkxst)]

That is a GC Deadlock.

Backporting the patch from the attached upstream bug may help a little bit, however the only real fix for this is to wait for updated javascript engine. While this should make it into Raring, unlikely it will make it into Precise.

[Tim Lunn (darkxst)]

There is a proper upstream fix for this now, we maybe able to backport that to Raring.

[Jeremy Bícha (jbicha)]

Thank you for reporting this bug to Ubuntu. I apologize that we are not always to respond to bug reports promptly. Ubuntu 12.04 LTS reached End of Life in April. See this document for currently supported Ubuntu releases: https://wiki.ubuntu.com/Releases

Please upgrade to Ubuntu 16.04 LTS and re-test. If the bug is still reproducible, increase the verbosity of the steps to recreate it so we can try again.

Do feel free to report any other bugs you may find.