[systemd-devel] How soon after login can I rely on systemd --user having reached sockets.target?

[Andrei Borzenkov]

On Mon, Oct 20, 2014 at 4:47 PM, Zbigniew Jędrzejewski-Szmek
<zbyszek at in.waw.pl> wrote:
> On Mon, Oct 20, 2014 at 02:16:30PM +0400, Andrei Borzenkov wrote:
>> On Mon, Oct 20, 2014 at 1:02 PM, David Herrmann <dh.herrmann at gmail.com> wrote:
>> > Btw., manager_check_finished() doesn't explicitly wait for
>> > default.target, but instead waits for all jobs to be done. Not sure
>> > why..
>>
>> Because default.target can be reached long before all jobs that are
>> part of transaction finish. Do not forget that Wants != After.
> It's confusing, but being Wanted by a target automatically adds a
> Before dependency.
>

But not every unit is directly WantedBy default.target, right?
default.target Wants A.service where A.service Wants B.service. Now
B.service is pretty much on free run, not?

>> > Anyway, this means any dynamically scheduled jobs will also
>> > contribute to this delay.
>> >
>>
>> OTOH it means that if your service has "systemctl start
>> other.service", other.service will contribute.
>>
>> I wonder - does it wait for *any* job or only for those started as
>> part of initial transaction? Arguably, the latter would be the right
>> semantic here, not?
> I guess that it didn't matter too much so far, given that an "empty"
> user session starts in tens of milliseconds. But not it's starting to
> matter and we should define something sane here.
>

I'm mostly concerned about system boot here to be honest ... the old
recurring question - how can we know that boot is complete.

> Allowing the initial transaction to complete is not good, becuase
> if one adds a job like "fetch all my mail", "preload the cache", or
> anything else which is perfectly reasonable but could take unbounded
> time, the user will be blocked out.
>
> default.target is better, but still to much I think. We need the
> equivalent of systemd-user-sessions.service or basic.target, that
> would mean "basic user infrastracture is in place and a shell
> or a graphical env can be launched, user sockets are open, even
> if the services are not fully there yet".
>
> Zbyszek
>
>