Re: [vserver] upstart and vserver

From: Jeff Jansen <>
Date: Tue 04 Jan 2011 - 02:14:11 GMT
Message-ID: <>

On Wednesday 22,December,2010 12:01 AM, Herbert Poetzl wrote:
> if you are interested in tracking this down, please pay a visit
> to the IRC channel (#vserver @ where we can debug
> this in detail (you need a test system and a kernel build tree
> to test with :)

I definitely would be interested in working on this. Pardoning my
ignorance, what timezone are you in? :-) I'm in UTC+8.

Right now I'm working on this in Virtual Box. So I've got Debian
Squeeze as the host running in Vbox and then Lucid as a vserver guest.
(I see exactly the same behavior in VBox as on a "real" server. Will
troubleshooting work in Virtual Box or do I need to install all this on
a physical server again?

>> If I go into "/etc/init/ssh.conf" and comment out the "expect fork" line
>> and then change 'exec sshd' to 'exec sshd -d' (so sshd won't fork), then
>> SSH starts and stops correctly using upstart.
> I presume this simply disables the ptrace completely,

Yes, exactly. The "expect fork/daemon" config line tells Upstart to use
ptrace to "follow" the program as it forks and exits, so it doesn't
record the wrong PID. By removing that and telling the program not to
fork and "daemonize", upstart properly tracks the PID without using ptrace.

> note that I'm not convinced that ptracing services is a good idea
> in the first place, mainly because of performance implications.

The upstart developer agrees with you. He says at this point he's
convinced ptrace is NOT the way to do this and is working on a rewrite
of the functionality for the next version. But no timeframe for the new
version nor does that solve the problem for distros like lucid which use
the present version.

Thanks again.

Jeff Jansen
Received on Tue Jan 4 02:14:33 2011

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