Hi, I'm hitting this quite consistently on Pop!_OS 19.04 in Virtualbox (Windows 10 host) on Lenovo T460.

Essentially, the CPU usage goes up to 100% for avahi-daemon, and the strace shows it stuck in a loop, reading/writing to a named pipe, like so:

poll([{fd=6, events=POLLIN}, {fd=14, events=POLLIN}, {fd=13, events=POLLIN}, {fd=12, events=POLLIN}, {fd=11, events=POLLIN}, {fd=10, events=POLLIN}, {fd=3, events=POLLIN}, {fd=8, events=POLLIN}], 8, 0) = 3 ([{fd=14, revents=POLLIN|POLLERR}, {fd=12, revents=POLLIN}, {fd=10, revents=POLLIN}])
write(7, "W", 1)                        = 1
write(7, "W", 1)                        = 1
read(6, "WW", 10)                       = 2
poll([{fd=6, events=POLLIN}, {fd=14, events=POLLIN}, {fd=13, events=POLLIN}, {fd=12, events=POLLIN}, {fd=11, events=POLLIN}, {fd=10, events=POLLIN}, {fd=3, events=POLLIN}, {fd=8, events=POLLIN}], 8, 0) = 3 ([{fd=14, revents=POLLIN|POLLERR}, {fd=12, revents=POLLIN}, {fd=10, revents=POLLIN}])
write(7, "W", 1)                        = 1
write(7, "W", 1)                        = 1
write(7, "W", 1)                        = 1
write(7, "W", 1)                        = 1
read(6, "WWWW", 10)                     = 4
poll([{fd=6, events=POLLIN}, {fd=14, events=POLLIN}, {fd=13, events=POLLIN}, {fd=12, events=POLLIN}, {fd=11, events=POLLIN}, {fd=10, events=POLLIN}, {fd=3, events=POLLIN}, {fd=8, events=POLLIN}], 8, 0) = 3 ([{fd=14, revents=POLLIN|POLLERR}, {fd=12, revents=POLLIN}, {fd=10, revents=POLLIN}])
^Cstrace: Process 782 detached


root@pop-os:/# ls -ltr /proc/782/fd
total 0
lrwx------ 1 root root 64 Sep 25 13:03 14 -> 'socket:[20288]'
lrwx------ 1 root root 64 Sep 25 13:03 13 -> 'socket:[20287]'
lrwx------ 1 root root 64 Sep 25 13:03 12 -> 'socket:[20286]'
lr-x------ 1 root root 64 Sep 25 13:03 11 -> anon_inode:inotify
lrwx------ 1 root root 64 Sep 25 13:03 10 -> 'socket:[20154]'
l-wx------ 1 root root 64 Sep 25 13:03 9 -> 'pipe:[20153]'
lr-x------ 1 root root 64 Sep 25 13:03 8 -> 'pipe:[20153]'
l-wx------ 1 root root 64 Sep 25 13:03 7 -> 'pipe:[20152]'
lr-x------ 1 root root 64 Sep 25 13:03 6 -> 'pipe:[20152]'
lrwx------ 1 root root 64 Sep 25 13:03 5 -> 'socket:[20141]'
lrwx------ 1 root root 64 Sep 25 13:03 4 -> 'socket:[19687]'
lrwx------ 1 root root 64 Sep 25 13:03 3 -> 'socket:[17872]'
lrwx------ 1 root root 64 Sep 25 13:03 2 -> 'socket:[19192]'
lrwx------ 1 root root 64 Sep 25 13:03 1 -> 'socket:[19192]'
lr-x------ 1 root root 64 Sep 25 13:03 0 -> /dev/null
root@pop-os:/# 


My avahi config is:

    ## /etc/avah/avahi-daemon.conf
    [server]
    use-ipv4=yes
    use-ipv6=no

    ratelimit-interval-usec=1000000
    ratelimit-burst=1000

    [wide-area]
    enable-wide-area=yes

    [publish]
    publish-hinfo=no
    publish-workstation=no

    [reflector]
    [rlimits]



The journal log is overgrown with messages like so: (I've replaced parts of the ipv6 addresses with XXXX)
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:485e:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:28d5:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:61:28d5:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:fca2:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:61:fca2:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:90ab:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:61:90ab:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:61:5855:XXXX:XXXX:XXXX9 on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:5855:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:94aa:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:61:94aa:XXXX:XXXX:XXXX on enp0s8.*.
Sep 25 10:34:11 pop-os avahi-daemon[782]: Registering new address record for 2606:b400:818:64:e973:XXXX:XXXX:XXXX on enp0s8.*.



I've managed to gather the 'perf' data, that was requested by lathiat.

Let me know if this info is of use.