Re: backend hangs at immediate shutdown (Re: Back-branch update releases coming in a couple weeks)

On Thu, Jun 20, 2013 at 12:33:25PM -0400, Alvaro Herrera wrote:
> MauMau escribi?:
> > Here, "reliable" means that the database server is certainly shut
> > down when pg_ctl returns, not telling a lie that "I shut down the
> > server processes for you, so you do not have to be worried that some
> > postgres process might still remain and write to disk". I suppose
> > reliable shutdown is crucial especially in HA cluster. If pg_ctl
> > stop -mi gets stuck forever when there is an unkillable process (in
> > what situations does this happen? OS bug, or NFS hard mount?), I
> > think the DBA has to notice this situation from the unfinished
> > pg_ctl, investigate the cause, and take corrective action.
>
> So you're suggesting that keeping postmaster up is a useful sign that
> the shutdown is not going well? I'm not really sure about this. What
> do others think?

It would be valuable for "pg_ctl -w -m immediate stop" to have the property
that an subsequent start attempt will not fail due to the presence of some
backend still attached to shared memory. (Maybe that's true anyway or can be
achieved a better way; I have not investigated.)

--
Noah Misch
EnterpriseDB http://www.enterprisedb.com