Re: [GENERAL] Shutting down a warm standby database in 8.2beta3

Magnus Hagander <mha@sollentuna.net>

From: "Magnus Hagander" <mha@sollentuna.net>
To: "Tom Lane" <tgl@sss.pgh.pa.us>
Cc: "Stephen Harris" <lists@spuddy.org>, <pgsql-hackers@postgresql.org>
Date: 2006-11-20T16:34:44Z
Lists: pgsql-hackers, pgsql-general
> > I haven't really been folliowing this thread. What exactly 
> is it you 
> > want to accomplish (maybe there is a different way to fix 
> it on win32)?
> > Kill a process along with all it's subprocesses?
> 
> Right.  The problem (as seen on Unix) is that if the recovery 
> subprocess is waiting for a recovery_command script to 
> complete, it doesn't react to SIGQUIT (because system() 
> ignores SIGQUIT) and the script doesn't react either (because 
> it never gets the signal at all).  We'd like "pg_ctl stop -m 
> immediate" to abort the script and then have the recovery 
> process fail, allowing restart later.  More generally, it 
> seems like any time a backend is executing system(), the 
> called script ought to be subject to SIGINT or SIGQUIT 
> signals sent to the backend by the postmaster.

Hm. ok. 
Well, first of all, the generic case will never really wrok - because we
send our own kind of signals, and a script (batchfile executing under
cmd.exe) or anythin non-postgresql-backedn will never respond to that
anwyay.

However, for this specific case we might be able to do something. pg_ctl
creates a job object that it assigns the postmaster to when it's started
if that works. (Won't work if pg_ctl itself is running inside a job
object, but normally it won't be doing that). That means that we could
have pg_ctl look up this job object and execute TerminateJobObject() on
it. That will kill all processes inside the job object (includnig
backends, but if we run it from pg_ctl *after* postmaster has shut down,
there should be none of those left).
(This will work for the generic processes as well, but it will *only*
work for the pg_ctl-stops-theprocess scenario, it can't be done from
inside the postmaster)

It's not entirely pretty (to say the least), but might be worthwhile
looking at?

//Magnus