Multiple quick clicks on launcher icon with multiple windows completely crashes Unity

Bug #731790 reported by Eylem
This bug affects 4 people
Affects Status Importance Assigned to Milestone
Fix Released
Jason Smith
compiz (Ubuntu)
Fix Released
unity (Ubuntu)
Fix Released

Bug Description

OK, this must be one of the most serious Unity bugs out there as it renders the GUI totally crippled. I've been trying to understand its mechanism and initially I thought it happened only with Libreoffice but no. Do the following to reproduce:
1) Start an application that may use multiple windows and open a few windows (multiple pdfs in Evince, multiple Libreoffice documents, multiple Nautilus or Firefox windows, etc., anything). Even better, start multiple of those applications.
2) Now the launcher icon indicates multiple windows and you can click on it multiple times (without letting the launcher hide) to see different phases for window selection/management. First click to bring the most recent window to front, second to show all windows so that you pick one, third to hide them all. I believe I got it right so far, right?
3) Now try double-clicking or triple-clicking on the launcher icon, really fast. Then, pause briefly and do it again or do the same to another multiple-windowed launcher icon. In my experience, after a few double-click/window-select actions, what happens is that the Unity window decorator suddenly crashes. The thing is it crashes so bad that not only all window decorations (borders and buttons therein), the launcher and the top panel are gone, the GUI becomes totally irresponsive to keyboard input. Mouse works but doesn't help you get anywhere as you cannot shift through open applications or type a command to restart Unity. Ctrl-Alt-Del does not work but somehow Ctrl-Alt-FX (X is in 1-9) works and you can do "sudo reboot". Anything unsaved is gone forever...

This happened to me quite often and it did not improve after so many Unity updates/bugfixes. I think it is very critical and it has to be resolved for Unity to be deployed in a production environment. I wish I could get a screenshot but if you can imagine from the above description, it's pratically impossible to get a screenshot from the system.

I searched for a duplicate bug but I couldn't find. Thank you in advance for taking care of this!

Revision history for this message
Paul Sladen (sladen) wrote :

Eylem: I'm sure you'll get a longer answer, for the moment, a workaround (that allows you to carry on, and/or save your work) is:

  killall -9 compiz
  unity --replace
  Ctrl-Alt-F8 (and wait 10-15 seconds for unity to "catch up"... for some reason it takes a long time to enumerate the existing open windows)

The other bug is that sometimes 'gnome-screensaver' opens (invisibly) on top of everything a "killall gnome-screensaver" from Ctrl-Alt-F1 will nuke that.

Revision history for this message
Eylem (eylemkoca) wrote :

Paul, thank you for this great tip! I knew something was borked but had no idea what process to kill and/or start.

I really hope a dev can pinpoint the problem and solve it. Please let me know if there is any log file or something that I should attach. Thanks!

Revision history for this message
Alex Launi (alexlauni) wrote :

This does sound serious. Could you please provide a stack trace by following the instructions provided at, and then attach the unity.log file to this report?

Changed in unity:
status: New → Incomplete
Changed in compiz (Ubuntu):
status: New → Incomplete
Changed in unity:
importance: Undecided → High
Changed in compiz (Ubuntu):
status: Incomplete → New
Changed in unity (Ubuntu):
importance: Undecided → High
status: New → Incomplete
Revision history for this message
Eylem (eylemkoca) wrote :

Alex, thank you for your attention! I did as you told and I am now attaching the unity.log file. I really hope it helps!

Revision history for this message
Eylem (eylemkoca) wrote :

Paul, your suggestion for a workaround does not work. I mean unity (or compiz) does not start, the command (unity --replace) terminates with segmentation fault and exits. So far I've been unable to recover from this crash. It's very serious and it doesn't take much to trigger it. I just had a crash when I had two Nautilus windows on two different workspaces and I clicked once on the Nautilus launcher icon: boom.

Revision history for this message
Eylem (eylemkoca) wrote :

I uploaded the unity.log file. Please let me know if you need anything else. Thanks!

Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :

Thanks for the log, I'm setting to triaged.

I can reproduce this issue but with I get 3 different type of bugs:
1. Unity / Compiz crash as described in the original report
2. Only unity-panel-service crashes
3. Nothing crashes but the icon in the launcher vanished and the app linked to this icon close suddenly (all the instances).

Changed in unity (Ubuntu):
status: Incomplete → Triaged
Revision history for this message
Jean-Baptiste Lallement (jibel) wrote :

Note that in the third case, the icon disappear, the windows of the application disappear too but the application is still running. It's just that it becomes invisible and there's is no way to make it come back.

Revision history for this message
Eylem (eylemkoca) wrote :

Jean-Baptiste, thank you for looking into this. I can confirm that I experienced both cases 1 and 3 as you put in comment #7.

I had case 1 with Evince, Libreoffice, Nautilus, and Gedit, and it seems like it doesn't matter what the application is.

I had case 3 with Evince, Libreoffice and Mathematica. Till your post I hadn't thought they were related. But both cases are triggered by clicks on the Launcher icons, and clicks don't have to be too many or too quick.

I can easily say that both cases become more probable as the Unity session uptime gets longer. I had reported another bug where long uptimes causes the Launcher not to hide or dodge. Might be related if there is some kind of degradation in Launcher (or Compiz?) as time goes (I'm not a developer, but I'm sure you can put this vague sentence into context).

I'm not sure what you mean by case 2. When it happens, window decorations are still there but the top panel and Launcher are gone? I don't think I had that one then...

Changed in unity:
status: Incomplete → Triaged
Neil J. Patel (njpatel)
Changed in unity:
assignee: nobody → Alex Launi (alexlauni)
milestone: none → 3.6.8
Revision history for this message
Eylem (eylemkoca) wrote :

I'm not sure if it's related by I've been experiencing this crash incredibly often after 3.6.6. Sure a lot of things were fixed but something got broken in the meantime. It's the same crash as above but it's being triggered by the simplest of things kind of spontaneously. Three times in the last hour! Once I clicked Alt-Shift-Up (Expo), once I was customizing Thunderbird toolbar, once I clicked Alt-Left in Nautilus.

Please take a look at this, I cannot be the only one...

Changed in unity:
milestone: 3.6.8 → 3.8
Changed in unity:
milestone: 3.8 → 3.8.2
Changed in unity:
milestone: 3.8.2 → 3.8.4
Revision history for this message
Neil J. Patel (njpatel) wrote :

Hi, we've fixed this with the latest unity (3.8.2), please re-open if it's still an issue, thanks!

Changed in unity:
assignee: Alex Launi (alexlauni) → Jason Smith (jassmith)
status: Triaged → Fix Released
Revision history for this message
Launchpad Janitor (janitor) wrote :
Download full text (5.7 KiB)

This bug was fixed in the package unity - 3.8.4-0ubuntu1

unity (3.8.4-0ubuntu1) natty; urgency=low

  * New upstream release.
    - [fglrx] compiz crashed with SIGSEGV in nux::IOpenGLSurface::UnlockRect()
      (LP: #685682)
    - SIGSEGV in g_atomic_int_get (LP: #688803)
    - unity-panel-service crashed with SIGSEGV in bamf_factory_view_for_path()
      (LP: #717684)
    - New window tracking system breaks in the case where windows try to
      restack relative to destroyed windows that were never mapped
      (LP: #723014)
    - Numpad 'Enter' doesn't work on highlighted items in dash, places-files and
      places-apps (LP: #741615)
    - compiz crashed with SIGSEGV in free() (LP: #738864)
    - compiz crashed with SIGSEGV in g_closure_invoke() (LP: #741674)
    - compiz crashed with SIGSEGV in CompWindow::id() (LP: #742028)
    - Windows that reparent away from the root before they are mapped can
      cause other windows to become invisible (and compiz to crash)
      (LP: #743011)
    - compiz crashed with SIGABRT in raise() (LP: #743414)
    - compiz crashed with SIGSEGV in g_object_get_qdata() (LP: #742905)
    - compiz crashed with SIGSEGV in g_closure_invoke() (LP: #748033)
    - compiz crashed with SIGSEGV in CompScreen::dpy() (LP: #751372)
    - compiz crashed with SIGABRT in __kernel_vsyscall() (LP: #744867)
    - unity-window-decorator crashed with SIGSEGV in gdk_window_get_events()
      (LP: #725284)
    - Missing icons in app launcher (LP: #728393)
    - Multiple quick clicks on launcher icon with multiple windows completely
      crashes Unity (LP: #731790)
    - Add a test case for invisible windows regressions (LP: #736876)
    - Re-sync with xquerytree to avoid stacking order issues (LP: #740465)
    - Wrong window moves (LP: #741656)
    - compiz crashed with SIGSEGV in g_cclosure_marshal_VOID__VOID()
      (LP: #742280)
    - panel superposition (LP: #742859)
    - unity-window-decorator doesn't start on secondary X session
      (LP: #730495)
    - Unity Launcher stops autohiding and is not responsive (LP: #744325)
    - dash categories dropdown menu leaves "ghost" on desktop (LP: #746800)
    - new dialogs open close enough of the launcher to make hide (LP: #747302)
    - dnd from the application place to the launcher works only once
      (LP: #747316)
    - compiz crashed with SIGSEGV in CompWindow::id() while opening tcl/tk
      interface of R (LP: #747439)
    - minimize animates window fading to the top left corner (ubuntu symbol)
      (LP: #747765)
    - Spread - Clicking on a app icon to spread the windows must always show
      all the windows, regardless of whether or not some of the windows are
      minimised (LP: #750349)
    - Launcher - Show visual de-coupling of Launcher app icons (LP: #751196)
    - unity-window-decorator crashed with SIGSEGV in event_filter_func()
      (LP: #748317)
    - Pressing Super-W to switch windows also presents Dash (LP: #753453)
    - Don't create windows over the launcher (LP: #688816)
    - Unity Grid is broken for multi-monitor setups (LP: #709221)
    - F10 key does not move focus to indicators when on the desktop.
      (LP: #727548)
    - dynamic ...


Changed in unity (Ubuntu):
status: Triaged → Fix Released
Changed in compiz (Ubuntu):
status: New → Fix Released
Revision history for this message
Mark Jeronimus (mark-jeronimus) wrote :

Still present in, or regressed to, version 7.4.0

The way I reproduced it is slightly different from OP: Repeat high speed clicking on a program icon with multiple windows until crash occurs. Crash is not total and windows are still usable but the launcher status looks crippled.

Launching `unity &` in a terminal fixes it, and it comes up with a crash reporter saying that the crash report is corrupt and cannot be processed.

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