[Bug 1819288] [NEW] avahi-daemon spinning, using 65% of a CPU after connection to Les Schwab wifi

Steve Langasek steve.langasek at canonical.com
Sat Mar 9 19:57:24 UTC 2019


Public bug reported:

After connecting to a guest wifi, I notice that avahi-daemon is using an
unreasonable amount of CPU time on my laptop.

gdb shows a busy loop in avahi_simple_poll_iterate().

strace output looks like:

write(7, "W", 1)                        = 1
write(7, "W", 1)                        = 1
read(6, "WW", 10)                       = 2
poll([{fd=6, events=POLLIN}, {fd=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {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=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {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=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {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=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {fd=12, revents=POLLIN}, {fd=10, revents=POLLIN}])
[...]

(repeats endlessly)

fd 6 and 7 are two ends of a pipe that avahi-daemon has open to itself.

It looks like avahi-daemon /eventually/ settles down, but this takes a
long time.

I'm not sure what to look for to explain this busy looping.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: avahi-daemon 0.7-4ubuntu2.1
ProcVersionSignature: Ubuntu 4.18.0-14.15-generic 4.18.20
Uname: Linux 4.18.0-14-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.10-0ubuntu13.2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sat Mar  9 11:27:05 2019
InstallationDate: Installed on 2010-09-24 (3088 days ago)
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
SourcePackage: avahi
UpgradeStatus: Upgraded to cosmic on 2018-10-18 (141 days ago)

** Affects: avahi (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug cosmic

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https://bugs.launchpad.net/bugs/1819288

Title:
  avahi-daemon spinning, using 65% of a CPU after connection to Les
  Schwab wifi

Status in avahi package in Ubuntu:
  New

Bug description:
  After connecting to a guest wifi, I notice that avahi-daemon is using
  an unreasonable amount of CPU time on my laptop.

  gdb shows a busy loop in avahi_simple_poll_iterate().

  strace output looks like:

  write(7, "W", 1)                        = 1
  write(7, "W", 1)                        = 1
  read(6, "WW", 10)                       = 2
  poll([{fd=6, events=POLLIN}, {fd=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {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=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {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=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {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=16, events=POLLIN}, {fd=15, 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}], 10, 0) = 4 ([{fd=16, revents=POLLIN}, {fd=13, revents=POLLIN}, {fd=12, revents=POLLIN}, {fd=10, revents=POLLIN}])
  [...]

  (repeats endlessly)

  fd 6 and 7 are two ends of a pipe that avahi-daemon has open to
  itself.

  It looks like avahi-daemon /eventually/ settles down, but this takes a
  long time.

  I'm not sure what to look for to explain this busy looping.

  ProblemType: Bug
  DistroRelease: Ubuntu 18.10
  Package: avahi-daemon 0.7-4ubuntu2.1
  ProcVersionSignature: Ubuntu 4.18.0-14.15-generic 4.18.20
  Uname: Linux 4.18.0-14-generic x86_64
  NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
  ApportVersion: 2.20.10-0ubuntu13.2
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Sat Mar  9 11:27:05 2019
  InstallationDate: Installed on 2010-09-24 (3088 days ago)
  InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
  SourcePackage: avahi
  UpgradeStatus: Upgraded to cosmic on 2018-10-18 (141 days ago)

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