I did a clean install (keeping my old home partition) of Ubuntu 12.04. Everything working fine, except the process avahi-daemon is consuming a lot (60-90%) CPU.
What is the avahi-daemon? Does it have something to do with Ubuntu One? I found guides on the internet on how to disable it, but I'm not eager to disable it, as it apparently has use.
Hardware: Dell Studio 1557, intel i5, AMD Radeon HD5470
Avahi is a free Zero Configuration Networking (Zeroconf) implementation, including a system for multicast DNS/DNS-SD service discovery. It allows programs to publish and discover services and hosts running on a local network with no specific configuration. For example you can plug into a network and instantly find printers to print to, files to look at and people to talk to. It is licensed under the GNU Lesser General Public License (LGPL). (Source: Wikipedia: Avahi (software))
You could try to restart the daemon by following:
Open up a terminal(CtrlAltT) and type: sudo service avahi-daemon restart.
18.04.2. However, I am seeing similar behavior on Raspbian 9 "stretch" with avahi-daemon eating up a high percentage of CPU after leaving it on for a while.
Jun 27, 2019 at 22:02
I don't understand why, but toggling WiFi off and then back on fixed this for me when the top answer (sudo service avahi-daemon restart) did not.
Update: it's because I connected to a different network. Still not sure why that makes a difference, but if you can, try switching.
Maybe the answer will come up here?
(Ubuntu 19.04)
In my case, one of my laptops uses a USB to RJ45 device. Once in a while (at least today it happened), when closing the laptop, the RJ45 may go berserk and start sending millions of packets non-stop. So fast and so bad that even Wireshark could not do anything about it and as you mentioned Avahi was going crazy (in my case it used around 33% CPU).
My WiFi would show the issue by not being able to keep up with the very high traffic, so as a result: no WiFi. (I have a similar issue when sending UDP packets on my network to handle some video system I'm working on). Note that did not completely kill the LAN network. I guess that's the advantages of having a 1Gbit switch...
To find the one connection that caused the problem, I had to disconnect each computer and see whether it "fixed" the WiFi. The WiFi itself was fine once that one laptop RJ45 was disconnected. I suspect that the USB device had just enough electricity from the RJ45 to continue to work when it should instead have been turned off.
Unless you're networking via wifi to other devices, just remove it totally with: "sudo apt-get remove avahi-daemon" - you'll be glad you did, for it can occasionally be a glitchy piece of work...
I've had problems with Avahi since Ubuntu 17.10 just trashing my wifi and disabling it requiring a reboot to get wifi back online. Just installed Lubuntu 18.04.5LTS on another laptop, and it began messing with my wifi on that computer too...
I also believe it can be a security risk allowing unauthorized computers to mess with my wifi. Occasionally I'd have two (2) sets of wifi bars in the panel - weird! Other times it would drop wifi, reload, drop again and not be able to reload without rebooting. I have no use for it at all...
I'm sure it can be valuable to some, but to novice users it can become an ongoing nightmare!!!
