git: 77e1ccbee3ed - main - rc: implement parallel boot

[Cy Schubert]

In message <4a4e021c-c874-5511-0e5a-4364df98e2c4 at freebsd.org>, Stefan Esser 
wri
tes:
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> From: Stefan Esser <se at freebsd.org>
> To: Cy Schubert <Cy.Schubert at cschubert.com>
> Cc: dev-commits-src-all at freebsd.org, src-committers at freebsd.org,
>  dev-commits-src-main at freebsd.org, Chris Rees <crees at bayofrum.net>,
>  Baptiste Daroussin <bapt at freebsd.org>, Rick Parrish <unitrunker at gmail.com>,
>  Alastair Hogge <agh at riseup.net>
> Message-ID: <4a4e021c-c874-5511-0e5a-4364df98e2c4 at freebsd.org>
> Subject: Re: git: 77e1ccbee3ed - main - rc: implement parallel boot
> References: <202102231027.11NARYYE041280 at gitrepo.freebsd.org>
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> Am 08.03.21 um 15:22 schrieb Cy Schubert:
> >> SDDM fails to successfully start an X session now, too.
> >>
> >> It repeatedly tries to start the X server without success.
> >> Only a "service sddm restart" terminates this loop.
> >>
> >> I do assume that the same applies to quite a number of services
> >> that are installed form ports/packages.
> >>
> >> While we can test parallel execution of rc scripts in base, this
> >> is not easily possible for the large number of optional services
> >> provided by ports/packages.
> >>
> >> I'll try to find the cause of the start-up failure for the SDDM
> >> case on my system. But even if I get it fixed on my system, it
> >> may still fail to start the X server on systems with a different
> >> set of ports ...
> >>
> >> Regards, STefan
> >=20
> > Is this new breakage after 763db589328 or before the fixes to this?
>
> This issue exists since the initial commit that enabled parallel start=20
> of rc scripts. I do not see why the X server does not start, since the
> commands that are started in parallel appear to be completely unrelated
> and I do assume that scripts are only started from the next line after
> the previous ones are running (but maybe not yet completely functional).

Yes, the original commit broke rc due to some incorrect assumptions by the 
author -- it messed up non-parallel boot here. I don't use parallel rc 
here. I think bapt@ does.

>
> SDDM is in the 2nd-last line of rcorder -p output on my system:
>
> 	/etc/rc.d/sendmail
> 	/usr/local/etc/rc.d/apache24
> 	/usr/local/etc/rc.d/postfix
> 	/etc/rc.d/othermta
> 	/etc/rc.d/bgfsck
> 	/usr/local/etc/rc.d/postgresql
> 	/etc/rc.d/securelevel
> 	/usr/local/etc/rc.d/sddm
>
> (All the above listed rc files are on a single line, actually.)

When I started looking at it, it uses spaces to separate related scripts to 
be started serially and line feeds for parallel threads.

>
>
> BTW: I was surprised to see the following line 139 in /etc/rc:
>
> files=`rcorder ${skip} ${skip_firstboot} /etc/rc.d/* ${local_rc}
> ${_rc_parallel} 2>/dev/null`
>
>
> Since ${_rc_parallel} is at the end of the command line, it does not
> have any impact on the output that is generated ...
>
> This seems to indicate that scripts from /usr/local/etc/rc.d are not
> executed in parallel, which makes the SDDM failure even more
> surprising.

I'll leave this to bapt@ and the author to answer. I suspect that this too 
wasn't tested, hence the suggestion that this not be MFCed for six weeks, 
or maybe never. The original commit seriously broke my infrastructure here.


-- 
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  https://FreeBSD.org
NTP:           <cy at nwtime.org>    Web:  https://nwtime.org

	The need of the many outweighs the greed of the few.