Re: [Nbd] [PATCH] nbd-server: add -D/-dont-daemonize option

["Dmitry V. Levin" <ldv@...1147...>]

On Mon, Jun 25, 2012 at 11:59:44AM +0200, Goswin von Brederlow wrote:
> "Dmitry V. Levin" <ldv@...1147...> writes:
> 
> > +        <term><option>-D</option></term>
> > +	<listitem>
> > +	  <para>Do not detach and do not become a daemon. This allows
> > +	  easy monitoring by service managers like systemd.</para>
> > +	</listitem>
> > +      </varlistentry>
> > +      <varlistentry>
> >          <term><option>-d</option></term>
> >  	<listitem>
> > -	  <para>Do not fork. Useful for debugging.</para>
> > +	  <para>Do not fork at all. Useful for debugging.</para>
> >  	</listitem>
> >        </varlistentry>
> >        <varlistentry>
> 
> I think the difference between -D and -d should be made clearer.
> 
> With -d the server runs in the foreground and accepts a single
> connection only and outputs debug infos, right?
> 
> With -D the server runs in the foreground but forks a child for every
> connect, right?

Yes.

> Also why should systemd care? It uses cgroups to monitor services. Isn't
> that one of the advantages of systemd over all the other service
> monitors?

The "simple" service type (when the service doesn't daemonize) has an
advantage: systemd can reliably differentiate between main process and
its children.

> What I would like to see is socket activation in nbd-server. That way
> the service can be started as needed without performance loss (other
> than the initial startup time once).

That shouldn't be a problem because nbd-server supports inetd mode.


-- 
ldv