[Bug 2065739] Re: Unnattended upgrades take a long time due to excessive running of "apt-check"

[Alistair Buxton]

For example look at .var.log.apt.history.log.txt

Many packages take less than a second to install. But in between each
one is a 15 to 20 second delay. That delay is the time during which apt-
check is running.

You can watch this happening by running "watch systemctl status apt-
daily-upgrade" and looking at the processes in the cgroup:

```
~$ systemctl status apt-daily-upgrade
● apt-daily-upgrade.service - Daily apt upgrade and clean activities
     Loaded: loaded (/lib/systemd/system/apt-daily-upgrade.service; static)
     Active: activating (start) since Tue 2024-05-14 23:01:03 BST; 1h 29min ago
TriggeredBy: ● apt-daily-upgrade.timer
       Docs: man:apt(8)
   Main PID: 29655 (apt.systemd.dai)
      Tasks: 11 (limit: 9299)
     Memory: 1.6G
        CPU: 1h 12min 57.651s
     CGroup: /system.slice/apt-daily-upgrade.service
             ├─ 29655 /bin/sh /usr/lib/apt/apt.systemd.daily install
             ├─ 29659 /bin/sh /usr/lib/apt/apt.systemd.daily lock_is_held install
             ├─ 29688 /usr/bin/python3 /usr/bin/unattended-upgrade
             ├─181903 /usr/bin/python3 /usr/bin/unattended-upgrade
             ├─181970 /usr/bin/python3 /usr/bin/unattended-upgrade
             ├─181978 sh -c "if [ -d /var/lib/update-notifier ]; then touch /var/lib/update-notifier/dpkg-run-stamp; fi; /usr/lib/update-notifier/update-motd-updates-available 2>/dev/null || true"
             ├─181980 /bin/sh -e /usr/lib/update-notifier/update-motd-updates-available
             ├─181994 /usr/bin/python3 /usr/lib/update-notifier/apt-check --human-readable
             └─182339 /usr/bin/python3 -Es /usr/bin/lsb_release -c -s
```

Then manually running "time apt-check"

```
~$ time /usr/lib/update-notifier/apt-check --human-readable
Expanded Security Maintenance for Applications is not enabled.
    
269 updates can be applied immediately.
45 of these updates are standard security updates.
To see these additional updates run: apt list --upgradable
    
33 additional security updates can be applied with ESM Apps.
Learn more about enabling ESM Apps service at https://ubuntu.com/esm
    
real   0m12.916s
user   0m11.012s
sys    0m1.885s
```

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https://bugs.launchpad.net/bugs/2065739

Title:
  Unnattended upgrades take a long time due to excessive running of
  "apt-check"

Status in unattended-upgrades package in Ubuntu:
  New

Bug description:
  The unattended upgrade services runs "apt-check" to update the MOTD
  where a summary of available updates is displayed. It does this after
  every package that is installed. Unfortunately, apt-check is extremely
  expensive - it takes about 15 seconds to run.

  If you have a computer that is infrequently used, you may have as many
  as 300 available updates. Unattended upgrade will therefore run apt-
  check 300 times. This takes 1 hour 15 minutes, during which time no
  packages are actually installed.

  Suppose you turn on your computer once a week to do something like pay
  some bills. It takes 5 minutes. Then you have to wait 2 hours before
  you can turn it off. Every time.

  ProblemType: Bug
  DistroRelease: Ubuntu 22.04
  Package: unattended-upgrades 2.8ubuntu1
  ProcVersionSignature: Ubuntu 5.15.0-71.78-generic 5.15.92
  Uname: Linux 5.15.0-71-generic x86_64
  ApportVersion: 2.20.11-0ubuntu82.4
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CurrentDesktop: Unity:Unity7:ubuntu
  Date: Wed May 15 00:17:47 2024
  InstallationDate: Installed on 2013-12-22 (3796 days ago)
  InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
  PackageArchitecture: all
  RebootRequiredPkgs: Error: path contained symlinks.
  SourcePackage: unattended-upgrades
  UpgradeStatus: Upgraded to jammy on 2023-04-16 (394 days ago)
  modified.conffile..etc.apt.apt.conf.d.10periodic:
   APT::Periodic::Update-Package-Lists "1";
   APT::Periodic::Download-Upgradeable-Packages "1";
   APT::Periodic::AutocleanInterval "0";
  mtime.conffile..etc.apt.apt.conf.d.10periodic: 2017-11-17T12:55:49.319695

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