Re: pidsig 0.11 - a fghack like de-daemonisation tool

[Laurent Bercot <ska-supervision@skarnet.org>]

> There is a weakness in this "strong supervision" model. Any service with a 
> 'down' file will not be restarted if its supervise/runsv or 
> svscan/runsvdir is replaced.

 If a branch of the supervision tree dies, the old subtree, including
leaves (i.e. services) is still alive. Manual admin intervention is
necessary to kill it off and recreate a new subtree, connected to init.
If there are any services with down files, but that need to be alive,
the admin can take care of them at that time.
 Now, if a service has a down file, and its supervisor dies, *and then*
the service dies too, then the service won't be restarted indeed; but
we're talking about a double failure, which should be uncommon.

 Nevertheless, down files are a decrease in reliability. They're practical
for test and manual intervention purposes, but I've never met a real-life
case where they are necessary. It's always possible to boot the machine
with a nearly-empty svscan directory and populate it during the later
initialization phases.

-- 
 Laurent