gnome-panel hangs on login with more than one weather applet

[Anton Lindström]

Binary package hint: gnome-panel

After upgrading to 9.10 from 9.04 gnome-panel hangs ~80% of the times when I log in. The panel is drawn but it is completely empty and doesn't respond when I click on it. I have to do CTRL-ALT-F1, log in, and kill it to make it reload. This works every time.

gnome-panel is not using any CPU or a lot of memory, it seems to be idling or waiting for something. I found a similar bug report, but in that case there was a 100% CPU usage, and the problem was triggered by changing the icon size of the panel. This is not the case for me. The only mention of this problem that I found was a thread in an ubuntu forum.

Ctrl-alt-delete still works and brings up the reboot/shutdown/etc dialog.

The package version is 1:2.28.0-0ubuntu6. I have created a backtrace and will attach it. Could one of the applets in the panel cause this??

Any help would be appreciated.

[Andre Spiegel (spiegel)]

I have the same problem. I only have a single panel at the bottom of the screen. The panel contains, among other things, two weather applets. When I log in, the panel hangs (about 80% of the time, as the original submitter reported). If I then do "killall gnome-panel" from the console, the panel becomes complete and responsive again, but the two weather applets are missing.

Maybe these applets have something to do with it?

[Pedro Villavicencio (pedro)]

could you install the libgdb2 dbgsym package and get a new one? also please get a full one with : thread apply all bt full on gdb thanks.

[Andre Spiegel (spiegel)]

I could provide this backtrace, but I don't understand what additional packages I should install. No packages by that name in synaptic. Can you explain?

[Anton Lindström (hlewagastir)]

I think #2 is right, the weather applets are the culprit. I've also got two and they do disappear after killing gnome-panel for me as well. Removing them seems to "solve" the problem, at least so far I haven't had any more cases of it hanging.

[Bubba (kprohn)]

I think this is related to Bug #466118 to which I have been subscribed. On 2009-11-25 I found that I could replicate this problem consistently on two different PC's and emailed the following information to a respondent of that bug.

"I'm a newbie, please bear with me. I saw your comments on Bug #466118 (Panel Crashes) on 9.10 and I wanted to provide some information. I had what seems to be a very similar problem with the panel not fully loading and no access to most items on the panel, including the menus. I had to exit by Ctl-alt-del and force a reboot by killing the panel (panel not responding msg). To successfully reboot, I often had to power down the PC and open with the "Fail-safe Gnome" option

9.10 also booted very slowly on my PC.

What I found seems to be associated with the three "Weather Report" app launchers on my top panel. (To watch my weather in Ohio and a son on each coast). I found that by removing the two extra launchers, the panel seems to work flawlessly on every normal restart.

I also did a clean install of 9.10 on another PC that I have and had the exact same results. I can consistently duplicate these results by adding a second or third weather report app launcher and rebooting. These PC's both have older 2 to 2.1Ghz AMD processors.

My three weather app launchers worked without a hitch in 9.04

I hope this information may be of some help. I would be glad to provide more information if needed."

[Andre Spiegel (spiegel)]

Here is another backtrace, taken in the state when the panel hangs. Not sure if I should try and include more debugging symbols, but I did use the gdb options that were suggested earlier in comment #3. Let me know if you need any further information.

[Lonnie Lee Best (launchpad-startport)]

My panel is getting corrupted a lot lately... Clock moving over to the left, unexpected changes of icon order on the top-right panel area, etc.

However, last night, I added the weather applet. This morning the panel wouldn't load. I had to use a live cd to delete /home/username/.gconf/apps/panel before I could boot up and load the panel.

Also, my firefox icon has been replace with a no-icon sign (crossed-out-red-circle). It launches firefox, but no firefox icon. Same goes in the applications > interent menu.

[normandrobert (sub1)]

I have the same problem after I added weather applets (3 currently). Like the others I can sometimes login without problems. I am happy to provide additional information if needed. Regards

[Bubba (kprohn)]

I have a similar (identical?) problem with intermittent panel freezes at boot. I have found ten other bugs with nearly identical trouble.
I have also discovered that I can recover my panel functionality with two steps that you may wish to try. This works 100% of the time on my machine.

Access a terminal (Ctl-Alt-F1) and execute the following command;

 $ killall gnome-panel

The second step is to return to the desktop (Ctl-Alt-F7) and open a "Run application" window (Alt-F2) and execute the command;

 $ gnome-panel --replace

My panels and system are completely functional now (except for missing weather apps). Do not use a desktop terminal for the second command - the process will hang in a terminal. See Bug #466118 for more comments.

Hope this works for you too...

[nitto (nitto)]

I'm affected by the same bug.

I usually solve in this way:
- Kill the gnome-panel on (Ctrl-Alt-F1) terminal
- return to desktop (Alt-F7)
- click where the log-out icon should be on the panel (the panel is completely empty but the icons on it works)
- I log-out
- I log-in again. This time the panel is fully working.

[Bubba (kprohn)]

Thanks nitto!
My bug may be slightly different however.
I just tried your solution in #11 and had fairly good success. I hammered my "test" machine with over twenty re-starts to get four failures. When I found the unresponsive panels I tried using the #11 method. I had good results 2 out of 4 times. Only twice did I fail to get active panels on the first re-login using that #11 method. A second execution of #11 worked well in those two instances.
It's still not a fix for me, but it seems to be a very good alternative.

[der_vegi (m-may)]

I just saw this on a machine with 9.10 I installed for someone, as well. Two weather applets => gnome-panel sometimes empty after login. Removed the panels => No problems any more.

[Bubba (kprohn)]

I would like to contribute a backtrace, but how do I run a gdb backtrace on gnome-panel when it only fails when rebooting or after killing the process? I have found several Ubuntu users with the same issue in other bug reports. They expressed that they were also unable to run a backtrace on gnome-panel under similar (or identical) circumstances.

Apparently we have all followed the wiki procedure for "already running programs ", only to find that we cannot reproduce the failure without killing the gdb trace program too!!!
Step 5 in already running programs illustrates the issue, because gnome-panel doesn't hang or crash at or after this point. Either the gnome-panel is already up and working or it is locked-up.

If the trace could be started after boot and before the gnome-panel initializes, that may work, but HOW?

If "pkill gnome-panel" or "killall gnome-panel" could be run in another terminal without terminating gdb, I think that would produce a very useful trace. Again, HOW??

I can run a backtrace after a successful initialization of gnome-panel or after a failed initialization, but I cannot catch the actual failure in progress.

Thank you...

[Bubba (kprohn)]

I am also a subscriber to several similar bugs, so I thought I would give Jeremy's test (Bug #491280) a shot. I followed the KernelMainline Builds directions and installed;

linux-headers-2.6.34-999_2.6.34-999.201004241005_all.deb
linux-headers-2.6.34-999-generic_2.6.34-999.201004241005_i386.deb
linux-image-2.6.34-999-generic_2.6.34-999.201004241005_i386.deb

As expected my Nvidia drivers would not work with this upstream kernel.

The system booted just fine for me. All 5 of my Weather Report Apps were functional. Since this is an intermittent problem I tried my proven method of making it fail. I opened a terminal window and pounded out 25 "pkill gnome-panel" commands and 25 "killall gnome-panel" commands. The panels refreshed flawlessly every time.

I rebooted my system - again no problem. I repeated the 25&25 terminal commands and again the panels refreshed flawlessly.

I have never been able to perform more than 7 of the pkill or killall commands without a panel failure much less one hundred times in a row.

I then uninstalled the Mainline Kernels and rebooted. It failed on the first reboot. The second reboot succeeded. After opening a terminal window and running the "pkill gnome-panel" again it failed on the fourth retry.

This next kernel may fix this bug and I suspect a few others.

[Per Ångström (autark)]

I'm seeing this regularly in Maverick.

Linux kernel 2.6.35-23-generic #40-Ubuntu SMP Wed Nov 17 22:14:33 UTC 2010 x86_64 GNU/Linux