debugging systemd ordering cycle

[Patrick Schleizer]

context:
- https://github.com/QubesOS/qubes-issues/issues/2193
- https://github.com/QubesOS/qubes-issues/issues/2198
- https://github.com/QubesOS/qubes-issues/issues/2194

Apparently not simple. I would appreciate suggestions on debugging
systemd ordering [and also dependency] cycles.

Something I found....

You need a newer version of systemd that provides systemd-analyze with
the verify command. systemd from jessie-backports works.

For 'dot': sudo apt-get install graphviz

>From http://unix.stackexchange.com/a/227963/49297

systemd-analyze verify default.target |&
perl -lne 'print $1 if m{Found.*?on\s+([^/]+)}' |
xargs --no-run-if-empty systemd-analyze dot |
dot -Tsvg >cycle.svg

The resulting graphic is so huge that I cannot make head or tail of it.

Cheers,
Patrick

[Marek Marczykowski-Górecki]

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Yes, I've tried this already.

Anyway I have already fixed those cycles - will push it in few hours.
And both qubes-db.service and qubes-mount-dirs.service will be before
local-fs.target, which is ordered before basic.target, so no extra
dependencies should be needed for services using qubes-db.

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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[Rusty Bird]

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Hi Patrick,

> I would appreciate suggestions on debugging systemd ordering [and
> also dependency] cycles.

If the cycle is relatively short, you could try opening a couple of
terminal windows and running "systemctl show" commands on each of the
mentioned units, to look at interesting property values with drop-ins
and defaults included:

systemctl show -p After,Before,Wants,Requires,RequiresOverridable \
-p Requisite,RequisiteOverridable,BindsTo,PartOf \
-p Conflicts,DefaultDependencies <unit> |
grep --color=never =.

Rusty
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