Gnome window list causes gnome-panel to eat all CPU

Bug #56289 reported by Aleksander Kamil Modzelewski
4
Affects Status Importance Assigned to Milestone
gnome-panel (Ubuntu)
Fix Released
Undecided
Ubuntu Desktop Bugs

Bug Description

I'm using gnome-panel 2.15.91-0ubuntu2 and gnome-applets 2.15.3-0ubuntu1 on Ubuntu Edgy. Using the window-list causes the gnome-panel slow down and take over all of the idle CPU (not slowing down the rest of the system, but still turning my laptop into an oven). Removing the window-list helps.

Tags: edgy
Revision history for this message
Mateusz Drożdżyński (matid) wrote :

Thanks for your bug report. Could you please take a look at bug 52405 and check whether your problem is related to it? Thanks in advance.

Changed in gnome-panel:
status: Unconfirmed → Needs Info
Revision history for this message
Aleksander Kamil Modzelewski (aleander) wrote :

Doesn't seem so. I know that bug and I have used a workaround mentioned in the comments (I have menu-xdg installed).

When I strace -p the gnome-panel and switch workspaces I see lots of
open("/usr/lib/X11/locale/common/xlcUTF-8.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/X11/locale/common/xlcUTF-8.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
(I have attached the strace) - but that's not related on the presence of the applet.

Another interesting symptom is that the applet slows down the panel gradually - but just removing the applet and adding it again doesn't help the issue (just removing does. Freshly started panel with the applet works ok, but slows down after some - not very long - time).

I am going to try some other debugging techniques mentioned in bug 52405 , but I'm inexperienced in debugging complex software and can take some time.

Revision history for this message
Sebastien Bacher (seb128) wrote :

Maybe you could run top and notice what program is using the CPU, then attach is with "gdb -p $(pidof program)" and get a backtrace with "thread apply all bt"?

Changed in gnome-panel:
assignee: nobody → desktop-bugs
Revision history for this message
Aleksander Kamil Modzelewski (aleander) wrote :

There's only one thread in gnome-panel. I have identified gnome-panel as the exact program, but it's the window list applet that causes the slowdown [disabling it causes the problem to go away]. I attached a gdb session to it and made several backtraces while the gnome-panel got slow. A new note: the cpu usage goes up only when switching workspaces/iconyfing some window/otherwise changing the appearance of the window-list. On other times the whole panel works ok. Applets working in separate instances (i.e. Tomboy) are not affected at all, but applets working "inside" gnome-panel process, like the gnome-menu, (I don't know the exact architecture, just noticed that some applets have their own processes, so sorry for inprecise wording) are all blocked of course.

I have attached the backtraces with some annotation.

Revision history for this message
Aleksander Kamil Modzelewski (aleander) wrote :

Oh. Sorry for long reply times - the bug is hard to reproduce, sometimes the window-list works correctly for many hours and sometimes it starts to get flaky after 30 minutes, and I still can't see how it is connected with what I do on the machine.

Revision history for this message
magilus (magilus) wrote :

What happens when you remove /etc/xdg/menus/debian-menu.menu?

If the problem disappears after clicking Applications then, the problem is a duplicate of #52405

Revision history for this message
Aleksander Kamil Modzelewski (aleander) wrote :

[I have missed that comment somehow]
Anyway, now the problem seems to have disappeared - I was using compiz without the window list in the meantime, and I think there were several updates in the meantime. I have removed debian-menu (along with the menu package), but this doesn't seem related to me - 1. I have applied another workaround (installed the package generating the debian-menu) 2. The problem was unrelated to the presence of the applications menu.

Revision history for this message
Sebastien Bacher (seb128) wrote :

Marking as fixed since it works now. Feel free to reopen if you get the issue again

Changed in gnome-panel:
status: Needs Info → Fix Released
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