Unity --replace gets stuck

[To Do]

Occasionally it happens that Unity is misbehaving in a way or another. Until Ubuntu 11.10 I would "unity --replace" and Unity would be back to normal.
After upgrading to Ubuntu Precise whenever I try using "unity --replace", it gets stuck in the middle, (Edge responsiveness...) and sometimes Unity would be functional again but if I close the terminal window or try to stop the process Unity hangs requiring a hard reboot.
I noticed I was getting some problems with BAMF not finding child processes but don't know what that means.
I tried using unity --reset and I got:
ERROR 2012-08-13 16:08:55 unity.glib-gobject <unknown>:0 g_object_unref: assertion `G_IS_OBJECT (object)' failed
It hung on: Setting Update "run_key"

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: unity 5.14.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-29.46-generic 3.2.24
Uname: Linux 3.2.0-29-generic i686
ApportVersion: 2.0.1-0ubuntu12
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,compiztoolbox,grid,snap,imgpng,mousepoll,resize,place,move,vpswitch,unitymtgrabhandles,regex,gnomecompat,wall,session,animation,fade,scale,expo,workarounds,ezoom,unityshell,switcher]
Date: Mon Aug 13 16:00:07 2012
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
SourcePackage: unity
UpgradeStatus: Upgraded to precise on 2012-05-13 (91 days ago)

[Daniel van Vugt (vanvugt)]

From what I gather the main problem here is:
"whenever I try using "unity --replace", it gets stuck in the middle, (Edge responsiveness...)"

Please clarify the description. What gets stuck? The mouse pointer? Is it the whole screen?

[To Do (entodoays)]

Let me clarify the problem:

Whenever there's a problem with Unity Dash or Launcher or Task switcher in the past I would use unity --replace.

After upgrading to Precise, whenever I do this the top bar disappears, the launcher as well, parts of the open windows remain visible and the mouse pointer continues to respond. I can even click on whatever is visible.

In the past everything would be back in place (Launcher, top bar) after a few seconds. Now it doesn't come back.

I cannot even press the power button to shutdown the pc. Alt-F2, Alt-F1 do absolutely nothing. I'm left with a hard shutdown the only option.

[Bilal Akhtar (bilalakhtar)]

Seems more like a compiz issue. I also run unity --replace often, and whenever it hangs, it's always Compiz' fault.

[Omer Akram (om26er)]

What I read from the comment of the reporter. unity is killed but not started again hence leaving user with undecorated windows. Not all the times but in very rare cases I have seen the exact thing on my machine as well.

[Launchpad Janitor (janitor)]

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

[Pieter Engelbrecht (chesedo)]

When running the "unity --replace" command in terminal the following output is given. Note that it gets stuck at the "run_key" operation and does not continue to the "autohide_panel" operation and others, so the window decoration is never restored.

Checking if settings need to be migrated ...no
Checking if internal files need to be migrated ...no
Backend : gconf
Integration : true
Profile : unity
Adding plugins
Initializing core options...done
Initializing composite options...done
Initializing opengl options...done
Initializing decor options...done
Initializing vpswitch options...done
Initializing snap options...done
Initializing mousepoll options...done
Initializing resize options...done
Initializing place options...done
Initializing move options...done
Initializing wall options...done
Initializing grid options...done
Initializing session options...done
Initializing gnomecompat options...done
Initializing animation options...done
Initializing fade options...done
Initializing unitymtgrabhandles options...done
Initializing workarounds options...done
Initializing scale options...done
compiz (expo) - Warn: failed to bind image to texture
Initializing expo options...done
Initializing ezoom options...done

(compiz:2474): GConf-CRITICAL **: gconf_client_add_dir: assertion `gconf_valid_key (dirname, NULL)' failed
Initializing unityshell options...done
WARN 2012-09-07 12:23:52 unity.libindicator <unknown>:0 Desktop file '/usr/share/applications/libreoffice-writer.desktop' is using a deprecated format for its actions that will be dropped soon.
WARN 2012-09-07 12:23:52 unity.libindicator <unknown>:0 Desktop file '/usr/share/applications/libreoffice-calc.desktop' is using a deprecated format for its actions that will be dropped soon.
ERROR 2012-09-07 12:23:52 unity.glib-gobject <unknown>:0 g_object_unref: assertion `G_IS_OBJECT (object)' failed
Setting Update "main_menu_key"
Setting Update "run_key"