[systemd-devel] [PATCHv2] core: do not spawn jobs or touch other units during coldplugging

[Lennart Poettering]

On Fri, 24.04.15 21:39, Andrei Borzenkov (arvidjaar at gmail.com) wrote:

> В Fri, 24 Apr 2015 20:19:33 +0200
> Lennart Poettering <lennart at poettering.net> пишет:
> 
> > On Fri, 24.04.15 20:46, Ivan Shapovalov (intelfx100 at gmail.com) wrote:
> > 
> > > On 2015-04-24 at 19:13 +0200, Lennart Poettering wrote:
> > > > On Fri, 24.04.15 20:06, Ivan Shapovalov (intelfx100 at gmail.com) wrote:
> > > > 
> > > > > With this patch applied, on `systemctl daemon-reload` I get the
> > > > > following:
> > > > 
> > > > Any chance you can do the same with debugging on? "systemd-analyze
> > > > set-log-level debug" right before the daemon-reload?
> > > > 
> > > > That should show the transaction being queued in.
> > > 
> > > Sure, I've ran it (log attached), but well... it did not show
> > > any new jobs being enqueued. But alsa-restore.service _did_ run and
> > > did reset my ALSA volume to the bootup value.
> > > 
> > > Pretty confused,
> > 
> > Note that starting services is recursive: if a service is enqueued,
> > then we add all its dependencies to the transaction, verify that the
> > transaction is without cycles and can be applied, and then actually
> > apply it.
> > 
> > This means, that starting a service foo.service, that requires
> > bar.target, that requires waldo.service, will mean that waldo.service
> > is also started, even if bar.target is already started anyway.
> 
> I was sure that on reload systemd simply restores previous state of
> services. Why it attempts to start anything in the first place?

well, sure it does restore it. but triggers might start someting after
reload, 

> It makes reload potentially dangerous; what if service was stopped on
> purpose and should remain this way?

well, the next time you start something and that something declares it
needs something else, then we will start that something else before
that something, and that's the right thing to do.

i mean, don't misunderstand what I wrote earlier: if a service is
already started, and you do a reload, then its deps will not be pulled
in again. Only newly enqueued start jobs will have that effect.

Lennart

-- 
Lennart Poettering, Red Hat