Process hierarchy on a DC?

[Andrew Bartlett]

On Thu, 2017-04-27 at 14:39 -0700, Jeremy Allison via samba-technical
wrote:
> On Thu, Apr 27, 2017 at 08:31:17PM +0200, Ralph Böhme wrote:
> > On Thu, Apr 27, 2017 at 09:23:48AM -0700, Jeremy Allison wrote:
> > > On Thu, Apr 27, 2017 at 12:04:58PM +0200, vl--- via samba-
> > > technical wrote:
> > > > Hi!
> > > > 
> > > > With current master 5701880655c8a82b6 I'm getting the following
> > > > process hierarchy (omitting the duplicate children):
> > > > 
> > > > 24963 ?        Ss     0:00 bin/samba
> > > > 24964 ?        S      0:00  \_ bin/samba
> > > > 24969 ?        S      0:00 bin/samba
> > > > 24971 ?        Ss     0:00  \_ /root/samba/bin/smbd -D --
> > > > option=server role check:inhibit=yes --foreground
> > > > 24991 ?        S      0:00      \_ /root/samba/bin/smbd -D --
> > > > option=server role check:inhibit=yes --foreground
> > > > 24979 ?        S      0:00 bin/samba
> > > > 24981 ?        Ss     0:00  \_ /root/samba/bin/winbindd -D --
> > > > option=server role check:inhibit=yes --foreground
> > > > 24990 ?        S      0:00      \_ /root/samba/bin/winbindd -D
> > > > --option=server role check:inhibit=yes --foreground
> > > > 
> > > > I think I remember that in the past this was all located under
> > > > one
> > > > "samba" process, now the winbind and smbd parents are
> > > > themselves
> > > > children of init. I could stop the DC with a single kill, now
> > > > it's
> > > > three.
> > > > 
> > > > Just curious: Why was this changed?
> > > 
> > > It's the tfork code. I'd bet good money on it :-).
> > > 
> > > samba_runcmd_send() which is used to invoke winbindd
> > > calls tfork() directly.
> > > 
> > > This is a side effect I missed in my review of
> > > the tfork code, but in my defense both Ralph
> > > and Metze who were the authors missed it too :-).
> > > 
> > > Ralph, Metze, ball is in your court I think :-).
> > 
> > looking into it. Shall we revert
> > 292e46ab12d8ec172c9d3b26330d8d6028a1d5a5 until
> > I have worked out something to address this? Currently researching
> > how to
> > inherit process group and session and *not* become our own process
> > group and
> > session leader.
> 
> Much though I hate to revert, I think this might be a good case
> for it temporarily.

Yeah, I think that might be the right thing in this case.  SambaXP
isn't the time to be rushing on this, and I think threading this though
the various constraints (keeping the other benefits but also the
process group) is going to be quite tricky.

Hopefully we can get a good testcase for this, perhaps also a unit test
running a small psudo-server for interactions with the process model
code?

Thanks,

Andrew Bartlett

-- 
Andrew Bartlett                       http://samba.org/~abartlet/
Authentication Developer, Samba Team  http://samba.org
Samba Developer, Catalyst IT          http://catalyst.net.nz/services/samba