group.of.nepali.translators team mailing list archive

[Launchpad Bug Tracker <1761096@xxxxxxxxxxxxxxxxxx>]

This bug was fixed in the package squid3 - 3.5.12-1ubuntu7.14

---------------
squid3 (3.5.12-1ubuntu7.14) xenial; urgency=medium

  * d/squid.resolvconf: Invoke "systemctl reload --no-block" if we are
    using systemd.  This prevents squid from blocking if the reload
    action is being issued indirectly because of another
    service (e.g., because dnsmasq has been restarted), which may
    cause a deadlock and prevent the whole transaction to
    complete. (LP: #1761096)

 -- Sergio Durigan Junior <sergio.durigan@xxxxxxxxxxxxx>  Fri, 04 Sep
2020 08:31:36 -0400

** Changed in: squid3 (Ubuntu Xenial)
       Status: Fix Committed => Fix Released

-- 
You received this bug notification because you are a member of नेपाली
भाषा समायोजकहरुको समूह, which is subscribed to Xenial.
Matching subscriptions: Ubuntu 16.04 Bugs
https://bugs.launchpad.net/bugs/1761096

Title:
  dnsmasq starts with error on Ubuntu Xenial amd64 when squid installed

Status in dnsmasq package in Ubuntu:
  Fix Released
Status in squid package in Ubuntu:
  Fix Released
Status in squid3 package in Ubuntu:
  Invalid
Status in dnsmasq source package in Xenial:
  Invalid
Status in squid source package in Xenial:
  Invalid
Status in squid3 source package in Xenial:
  Fix Released
Status in dnsmasq source package in Bionic:
  Invalid
Status in squid source package in Bionic:
  Invalid
Status in squid3 source package in Bionic:
  Incomplete

Bug description:
  [Impact]

  When using dnsmasq along with squid on Ubuntu Xenial, the user will
  experience a deadlock while performing on every second execution of
  the "systemctl start dnsmasq.service" command.  The deadlock will be
  caused by an attempt to invoke, by nss-lookup.target, a "systemctl
  reload squid.service", which will itself try to start the nss-
  lookup.target, which will be waiting on squid, therefore eventually
  leading to a timeout.

  The underlying cause of this deadlock is related to how systemd used
  to handle dependencies between multiple jobs being started in the same
  transaction.

  [Test Case]

  One can reproduce the issue on a Xenial container:

  $ lxc launch ubuntu-daily:xenial squid-bug1761096
  $ lxc shell squid-bug1761096
  # apt update
  # apt install squid dnsmasq -y

  It is quite possible that during "apt install" the bug will manifest,
  and dnsmasq will fail to start due to a timeout.  The user might see a
  message like:

  Job for dnsmasq.service failed because a timeout was exceeded. See
  "systemctl status dnsmasq.service" and "journalctl -xe" for details.

  If the bug doesn't manifest itself during installation, the following
  commands in sequence should trigger it:

  # systemctl restart dnsmasq.service
  # systemctl restart dnsmasq.service

  [Regression Potential]

  This change only touches the mechanism by which squid has its
  configuration reloaded in case of a DNS resolver change.  Because
  "systemctl reload --no-block" returns practically immediately, if
  squid's configuration file is invalid the user won't see any
  notifications.  However, this behaviour is already present currently,
  because "systemctl reload squid" invokes "/etc/init.d/squid reload";
  the user has to check "journalctl -u squid.service" if she wants to
  verify whether there were any failures during the reload.

  Other than that, and because systemctl will offload the service to the
  SysV script as usual (in the case of squid), I don't foresee any
  potential regressions.

  [Original Description]

  Setup to reproduce:

  Ubuntu Xenial amd64 net install iso from
  http://archive.ubuntu.com/ubuntu/dists/xenial/main/installer-
  amd64/current/images/netboot/mini.iso

  Install system with mostly defaults + LVM + OpenSSH server

  Note that this bug applies to both DHCP and static IP+DNS network
  configurations

  Once server rebooted and is available, log in and install dnsmasq + squid:
  apt-get update && apt-get install squid dnsmasq

  output of this can be found at https://pastebin.com/9Atuipju
  journalctl -xe output at https://pastebin.com/uLhfM4jN

  Furthermore at this point I can run alternating errors

  root@ubuntu-min:~# date ; service dnsmasq start ; date
  Wed Apr  4 09:18:07 CEST 2018
  Wed Apr  4 09:18:07 CEST 2018
  root@ubuntu-min:~# date ; service dnsmasq stop ; date
  Wed Apr  4 09:18:39 CEST 2018
  Wed Apr  4 09:18:39 CEST 2018
  root@ubuntu-min:~# date ; service dnsmasq start ; date
  Wed Apr  4 09:19:10 CEST 2018
  Job for dnsmasq.service failed because a timeout was exceeded. See "systemctl status dnsmasq.service" and "journalctl -xe" for details.
  Wed Apr  4 09:20:40 CEST 2018
  root@ubuntu-min:~# date ; service dnsmasq start ; date
  Wed Apr  4 09:42:57 CEST 2018
  Wed Apr  4 09:42:57 CEST 2018
  root@ubuntu-min:~# date ; service dnsmasq stop ; date
  Wed Apr  4 09:43:14 CEST 2018
  Wed Apr  4 09:43:14 CEST 2018
  root@ubuntu-min:~# date ; service dnsmasq start ; date
  Wed Apr  4 09:43:26 CEST 2018
  Job for dnsmasq.service failed because a timeout was exceeded. See "systemctl status dnsmasq.service" and "journalctl -xe" for details.
  Wed Apr  4 09:44:56 CEST 2018

  and so on... Each and every 1 out of 2 stop/start cycle fails in 1m30s
  timeout

  Complete journalctl -xe output attached

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1761096/+subscriptions