Re: Postgresql goes down need to restart (redhat postgresql service script) lock files removal avoid 2 postmasters

Bruno, Thanks for your help.

i checked - grep in the /etc/rc.d/init.d agrees with what you said - those
/var/lock and /var/run files are commonly placed in all of the services!

Here's my problem:

I had 4 out of 5 machines that got creamed this weekend, and all i needed to
go in for was to erase that file /var/lib/pgsql/data/postmaster.pid.
the same thing!!! (with only one machine) happened about a month ago.

I notice that in his script Lamar does this

pid=`pidof -s postmaster`
if [ $pid ]
then
echo $"Postmaster already running."
else
#all systems go -- remove any stale lock files
rm -f /tmp/.s.PGSQL.* > /dev/null
then he starts up pg_ctl.

What I would be doing is simply adding in

rm -f /var/lib/pgsql/data/postmaster.pid line.

It looks like he isnt worried about getting rid of that tmp/.s.PGSQL.* file
as long as he ran pidof first -
(is /tmp/.s.PGSQL. also a kind of lock file? i dont know - do you know
what system sets it up?)

Also - what do you do about those files

/tmp/.s.PGSQL.* ?

and what do you do about the possibility of supervise starting more than one
of the postmasters?

I like the idea of supervise starting me up again even without a reboot! and
i just want to catch this problem and solve it.

Thanks, mitchell

> On Thursday 08 May 2003 03:48 pm, you wrote:
> On Thu, May 08, 2003 at 14:39:08 -0400,
>
> mlaks <mlaks(at)bellatlantic(dot)net> wrote:
> > now we would not want to kill the postmaster, of course. But should we
> > even be TERM'ing the postmaster? I dont know. What do the Postgresql
> > Gurus say?
>
> I regularly use svc -d to shutdown postmaster and svc -u to restart it.
> This works just fine.
>
> > Moreover, if we agree that we need to imbed pg_ctl or postmaster in a
> > script to handle the above things, it should be doable to handle all of
> > the assorted other files if they are neccesary to handle .
>
> You don't have to do that.
>
> > Also what would be the problem in checking for the existence of a
> > postmaster and if none exists then killing the lock files.
>
> I would be very leary of putting this in a script. postmaster already does
> this and trying to be smarter than it might cause you a lot of grief.
>
> > My main problem is that I have machines that get creamed by power surges,
> > and then wont restart postgresql on reboot of the system because of the
> > damn lock files. I really want to deal with them up front!
>
> Most of the time when I have unscheduled shutdowns postgres comes up
> without problem. I don't remember if I have had any since I switched to
> using supervise though. I have had more issues with someone needing to
> answer a question from fsck from the console than postgresql not coming up.
>
> > MOreover can you tell me more about what init uses the locks for?
>
> To tell if the service is already running or not.
>
> > what is the role of the files
> >
> > /var/run/postmaster.pid
> > /var/lock/subsys/postgresql
> >
> > that Lamar carefully adds and subtracts?
>
> I don't know exactly, but I would expect that the pid file is a lock for
> the service and that the subsys file is a lock to keep two init scripts
> from running for the same time for the same service.
>
>
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