systemctl completion is slow

[Serhiy]

Every time I'm trying to autocomplete some service name for systemctl command it takes up to 5 seconds to do it.

AFAIU the file is /usr/share/bash-completion/completions/systemctl but I haven't read it yet.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: bash-completion 1:2.1-4ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-21.21-generic 3.19.8
Uname: Linux 3.19.0-21-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CurrentDesktop: KDE
Date: Mon Jul 6 12:33:40 2015
PackageArchitecture: all
SourcePackage: bash-completion
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Evgeny Markov (evgenymarkov)]

This bug appears in journalctl too. I observe this behavior in every distro.

[Evgeny Markov (evgenymarkov)]

So.. In latest Ubuntu 16.04 i see big improvements in systemd completion speed. It works almost instantly.

[Behrooz Amoozad (behrooz0az)]

same here, it's much much worse than ubuntu(17.10) in archlinux. I don't know what is different there but it might give you some clue if you do know.

[Brandon Bell (brandonbell)]

I suppose it depends on your definition of 'instantly'. While it doesn't always take 5+ seconds for me, it does take around 3 seconds and sometimes longer in Bionic (18.04.1 LTS).

Any other completion on my system happens in an estimated 25-100ms. Even completing 'apt-cache show', which returns over 64,000 results, still happens in less than a quarter second.

So I don't consider this issue resolved.

[Damiön la Bagh (kat-amsterdam)]

When is the fix going to be released? 18.04.1LTS takes still around 10 seconds to complete after

sudo systemctl start nameofser{TAB}

[Eliezer Croitoru (eliezer)]

A fix and enhancement was submitted at:
https://github.com/systemd/systemd/issues/7185#issuecomment-455410941

and seems to improve this a lot..
The main issue is with `systemctl start <TAB>` and the results can be seen for a search like:
`systemctl start apac<TAB>`.

[halfgaar (wiebe-halfgaar)]

For me the main issue is 'journalctl -u <TAB>'. Not always, but often this takes very long. I just time a run of 38 seconds, on a 8 core 32GB machine. A process called 'journalctl -F _SYSTEMD_UNIT' takes 100% CPU doing it.

If systemd is going to replace traditional rotated log files where you can just do 'cat logfile|grep', this kind of thing should really be fixed.

[halfgaar (wiebe-halfgaar)]

It gets worse. On one particular server, 'journalctl -u <tab>' takes an infinite amount of time. 'journalctl -F _SYSTEMD_UNIT' prints out lines like this forever:

session-1033145.scope
session-1033143.scope
session-1033140.scope
session-1033138.scope
session-1033136.scope

See it in action:

https://files.halfgaar.net/permanent/2022-07/20220720_1016_journalctl_tab_hang_launchpad_1471723.mp4