RE: SIGQUIT on archiver child processes maybe not such a hot idea?

From: David Steele [mailto:david@pgmasters.net]
> > Can't we use SIGKILL instead of SIGINT/SIGTERM to stop the grandchildren,
> just in case they are slow to respond to or ignore SIGINT/SIGTERM?  That
> matches the idea of pg_ctl's immediate shutdown.
> 
> -1, at least not immediately.  Archivers can be complex processes and
> they should be given the chance to do a graceful shutdown.

I agree that the user's archiver program should receive the chance for graceful stop in smart or fast shutdown.  But I think in immediate shutdown, all should stop immediately.  That's what I expect from the word "immediate."

If the grandchildren left running don't disturb the cleanup of PostgreSQL's resources (shared memory, file/directory access, etc.) or restart of PostgreSQL, we may well be able to just advice the grandchildren to stop immediately with SIGINT/SIGTERM.  However, for example, in the failover of shared-disk HA clustering, when the clustering software stops PostgreSQL with "pg_ctl stop -m immediate" and then tries to unmount the file systems for $PGDATA and archived WAL, the unmount  may take time or fail due to the access from PostgreSQL's grandchildren.


Regards
Takayuki Tsunakawa