avahi-daemon causes long delays at shutdown

[Brian Candler]

Ubuntu 14.04 server amd64 (text console only, no X)

At shutdown time, on a server which has a large number of interfaces, avahi-daemon causes delays of approximately 10 seconds per interface.

On this test system (Mac Mini): it normally takes 2 seconds from typing "reboot" to the screen going black. But if avahi-daemon is installed:

* with lo + eth0 in /etc/network/interfaces it takes 12 seconds
* with lo + eth0 + eth1 in /etc/network/interfaces it takes 22 seconds
* with lo + 36 other interfaces in /etc/network/interfaces it takes slightly over 6 minutes.

The latter system has these:

auto lo
auto tap9
auto br9
auto tap8
auto br8
auto tap7
auto br7
auto tap6
auto br6
auto tap5
auto br5
auto tap4
auto br4
auto tap3
auto br3
auto tap2
auto br2
auto tap1
auto br1
auto eth1
auto br-wan
auto eth0
auto tap10
auto tap11
auto tap12
auto tap13
auto tap14
auto tap15
auto tap16
auto tap17
auto tap18
auto tap19
auto br-lan
auto br-lan:0
auto br-lan:1
auto eth0.255
auto br-svc

Of these, only four have static IP addresses, and one has a DHCP address. The others exist purely to create internal bridges and taps.

It was very hard to isolate this bug, given that no messages are shown at shutdown (separate bug #1342856 for that)

But consistently if I do
  apt-get remove avahi-daemon
the problem goes away (it becomes 2 or 3 seconds to shutdown)

and
  apt-get install avahi-daemon
brings it back.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: avahi-daemon 0.6.31-4ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-30.55-generic 3.13.11.2
Uname: Linux 3.13.0-30-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
Date: Wed Jul 16 17:22:13 2014
InstallationDate: Installed on 2014-07-16 (0 days ago)
InstallationMedia: Ubuntu-Server 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
ProcEnviron:
 LANGUAGE=en_GB:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: avahi
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.