Comment 6 for bug 1741767

Thank you for reply, Carlo!

I have already disabled systemd timers for APT and removed unnattended-upgrades package.

So before running Muon I have the following dates:

$ ls -lt /var/lib/apt-xapian-index/update-timestamp /var/lib/dpkg/status /var/cache/apt/pkgcache.bin
-rw-r--r-- 1 root root 4812978 фев 19 01:49 /var/lib/dpkg/status
-rw-r--r-- 1 root root 49338939 фев 18 17:21 /var/cache/apt/pkgcache.bin
-rw-r--r-- 1 root root 0 фев 17 22:07 /var/lib/apt-xapian-index/update-timestamp

Then I started Muon and waited 5 minutes:

$ ls -lt /var/lib/apt-xapian-index/update-timestamp /var/lib/dpkg/status /var/cache/apt/pkgcache.bin
-rw-r--r-- 1 root root 4812978 фев 19 01:49 /var/lib/dpkg/status
-rw-r--r-- 1 root root 0 фев 18 17:21 /var/lib/apt-xapian-index/update-timestamp
-rw-r--r-- 1 root root 49338939 фев 18 17:21 /var/cache/apt/pkgcache.bin

then closed Muon.

After this I have interesting process in `ps aux | grep xapian`:

 /usr/bin/python3 /usr/share/apt-xapian-index/update-apt-xapian-index-dbus

I opened Muon again, waited 5 minutes and tried to search for `scilab` - it does not return results, after closing Muon I have:

$ ls -lt /var/lib/apt-xapian-index/update-timestamp /var/lib/dpkg/status /var/cache/apt/pkgcache.bin
-rw-r--r-- 1 root root 4812978 фев 19 01:49 /var/lib/dpkg/status
-rw-r--r-- 1 root root 0 фев 18 17:21 /var/lib/apt-xapian-index/update-timestamp
-rw-r--r-- 1 root root 49338939 фев 18 17:21 /var/cache/apt/pkgcache.bin

I run `sudo update-apt-xapian-index --force`:

$ sudo update-apt-xapian-index --force

The index /var/lib/apt-xapian-index is up to date, but rebuilding anyway as requested.
Reading .desktop files from /usr/share/app-install/desktop/: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-security_universe_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_yannubuntu_boot-repair_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_webupd8team_java_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-security_multiverse_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_outwiker-team_ppa_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_multiverse_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_restricted_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_jonathonf_firefox-esr_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_ubuntu-desktop_ubuntu-make_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_universe_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-backports_universe_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial_universe_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_nilarimogard_webupd8_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_atareao_atareao_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-updates_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-security_restricted_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_alexx2000_doublecmd_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_anonbeat_guayadeque_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_pulb_mailnag_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_libreoffice_libreoffice-5-4_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial_restricted_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_webupd8team_y-ppa-manager_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial_multiverse_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-backports_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.canonical.com_ubuntu_dists_xenial_partner_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial-security_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_ubuntu-sdk-team_ppa_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Reading en translations from /var/lib/apt/lists/ppa.launchpad.net_wereturtle_ppa_ubuntu_dists_xenial_main_i18n_Translation-en: done.
Rebuilding Xapian index: done.

$ ls -lt /var/lib/apt-xapian-index/update-timestamp /var/lib/dpkg/status /var/cache/apt/pkgcache.bin
-rw-r--r-- 1 root root 4812978 фев 19 01:49 /var/lib/dpkg/status
-rw-r--r-- 1 root root 0 фев 18 17:21 /var/lib/apt-xapian-index/update-timestamp
-rw-r--r-- 1 root root 49338939 фев 18 17:21 /var/cache/apt/pkgcache.bin

So timestamp of `/var/lib/apt-xapian-index/update-timestamp` did not change.

Started Muon again, now it is able to search `scilab` packages.

I'll try to monitor timestamps again and report back.