Update-mime-database is getting very slow during apps installation

[Antonio Solida]

The installation of some apps has become very slow due to the update-mime-database command that takes up a lot of time.

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: shared-mime-info 1.10-1
ProcVersionSignature: Ubuntu 4.18.0-15.16-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu13.2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Feb 19 22:37:53 2019
InstallationDate: Installed on 2019-01-16 (34 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 SHELL=/bin/bash
SourcePackage: shared-mime-info
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Pierre-Antoine Champin (pchampin)]

Same problem with 20.04.

I believe this is related to this issue: https://bbs.archlinux.org/viewtopic.php?id=255817 .

FTR, as `apt-daily.service` is running on startup, this was also increasing my boot-time significantly (although I found a workaround for this particular problem). Just to emphasize that this is a serious bug.

[Sebastien Bacher (seb128)]

Could you give some details on how you workarounded the startup issue?

[yurx cherio (cherio)]

This has been a disk muncher for over a year now. The way I know the update is running through mime database is I hear my disks going into grinding mode.

[Pierre-Antoine Champin (pchampin)]

@Sebastien Sorry for the late reply.

I recall that the workaround consisted in adding a random delay to the apt-daily task, so that it would not happen *right* at startup.

How exactly this was done, unfortunately, I didn't write it down :-/ but I think it was adding or creating the file ./system/apt-daily.timer, ensuring that it contained the RandomizedDelaySec directive.