Re: How to kill runsv, no matter what?

[prj@po.cwru.edu (Paul Jarc)]

"Daniel Clark" <dclark@pobox.com> wrote:
> the original daemontools seems to work with services with this "bug"

Yes, but only because it makes no attempt to ensure that log data is
written before the logger is shut down.

> and both daemontools and (I think) runit have a suite of tools to
> hack around issues with services that aren't designed to work with
> the supervision model of service control (e.g. the thing that forces
> processes to stay in the foreground).

That's true, but those are just the easy workarounds, and they're
imperfect.  (E.g., they don't relay signals.)  Reliably handling log
data and simultaneously working around services that leave stray child
processes is a hard problem, and the easiest solution known so far is
to fix each individual service.

> Actually, perhaps that would be the best way to deal with this - some
> small binary that can be used instead of exec in "run" scripts that
> has the property of killing all of its child processes when it dies -
> would something like that be feasible?

That could work for some cases (but, like pgrphack et al., it would be
sandwiched between exec and the real service, not used in place of
exec).  It would have to initially put itself in its own process
group, relay SIGTERM to every process in that process group, and relay
other signals to its immediate child.  But this won't help if the
service or its children put themselves in their own process group.
Also, SIGKILL and SIGSTOP can't be relayed, so you lose functionality
there too.  So fixing the service still remains an attractive option.


paul