monline

The phenomenon is nothing new: there're at least a dozen bug reports on gnome-panel eating up CPU and/or RAM.
Eg.:

• #461106 - gnome-panel starts consuming 75% or more of the CPU and becomes unresponsive
• #187540 - gnome-panel freeze when 8 windows are open when the panel is vertical (and here's a related forum thread)

In my case it happens on a multi-user server (used as "terminal server") with Ubuntu 8.10 (Hardy). Gnome-panel runs just fine most of the time, but occasionally an instance appears eating up 100% of one of the CPUs. Luckily these gnome-panel processes are just "remnants" (probably from a previous session of a user) since they have a parent process id of 1 and if the users are logged in, I always see another gnome-panel for them that is doing the panel rendering in their active session.

So the fix is easy: I can just kill all gnome-panel processes that are children of the init process (PID=1). To make this automatic, I added the following one-liner to /etc/crontab of the terminal server:

It runs the pkill -P 1 gnome-panel command every two minutes. I had no complaints about CPU-eating gnome-panel processes ever since.