avahi daemon uses a lot of CPU when network is not availiable

[Denis Rut'kov]

The avahi daemon can use up to 60% of CPU (I have a Pentium-M 1.73 Ghz) when the network is physically disconnected.

[Trent Lloyd (lathiat)]

Hi Denis,

Unfortunately this bug report isn't too helpful to us as there are no more details.

Is this a common problem you see? Does it happen every time? Once off?

Thanks,
Trent

[Denis Rut'kov (dendron2000)]

Hi. Yes, I understand this isn't too helpful, but I have no idea what else I can tell about this bug. It happens every time when system boots up with wi-fi switched off and ethernet cable is physically disconnected. It's 100% reproducible.

Here is my /etc/network/interfaces file

auto lo
iface lo inet loopback

auto airnet
iface airnet inet ppp
pre-up ip link set eth0 up
provider airnet

iface eth0 inet static
address 192.168.128.161
netmask 255.255.0.0

auto eth0

As you can see I have a pptp connection named airnet set up at start up. Maybe the problem is somehow concerned with that.

[Robert Ancell (robert-ancell)]

Is this still occurring in Ubuntu 8.10 or 9.04?

[Romel R. Sandoval-Palomo (romel-lavabit)]

This still occurring in Ubuntu 8.10 (powerpc). I don't know on other platforms.

[Li Li (lli5)]

Could reproduce this in Karmic (x86 and Dove).

[Nicola Ferralis (feranick)]

Still there in 10.10.

[J G Miller (jgmiller)]

Are the Ubuntu Avahi packagers even aware of this serious bug which causes 100% cpu usage?

"daemon infinite loop triggered by an empty UDP packet"

https://bugzilla.redhat.com/show_bug.cgi?id=667187

[Robert Ancell (robert-ancell)]

J G Miller: That patch is in Natty

[hamish (hamish-b)]

I suspect they are actually unrelated to the (?)DNS timeout(?) of this bug, but for the 100% cpu use on null UDP packet bug see also #655835 and #546231.

(if Denis has no network, there's small chance someone has sent him a null packet, and I think(?) this bug report predates the avahi patch which caused that null packet DoS situation. at least two different things going on here)

Hamish

[Phillip Susi (psusi)]

If this is still happening, can you capture an strace log on the process?