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Thread: Acting on dropped/timed-out connections

Acting on dropped/timed-out connections

From
"Milen A. Radev"
Date:
Hi list!

We have a daemon programme that acts as a pgsql client. It writes in a
DB the status of its own clients. And we have a different daemon that
needs to read that status information and decide upon it. The problem
is that the first daemon is a little fragile and from time to time it
crashes. I need to be able to monitor its connection to the PgSQL and
if it drops (times-out) to mark the status of all of its clients as
"unavailable" or "unknown".

At first I thought about attaching a trigger to pg_stat_activity
table, so on delete I could take action. The only problem was it is
not a table.

Any ideas?


--
Milen A. Radev

Re: Acting on dropped/timed-out connections

From
Roman Neuhauser
Date:
# mradev@gmail.com / 2005-09-08 11:31:25 +0300:
> We have a daemon programme that acts as a pgsql client. It writes in a
> DB the status of its own clients. And we have a different daemon that
> needs to read that status information and decide upon it. The problem
> is that the first daemon is a little fragile and from time to time it
> crashes. I need to be able to monitor its connection to the PgSQL and
> if it drops (times-out) to mark the status of all of its clients as
> "unavailable" or "unknown".

    Do you prefer knowing that the daemon failed, or having it
    automaticly restarted the very same moment it crashes? If the
    latter, take a look at djb's daemontools, or one of its open source
    lookalikes (http://smarden.org/runit/,
    http://offog.org/code/freedt.html).

--
How many Vietnam vets does it take to screw in a light bulb?
You don't know, man.  You don't KNOW.
Cause you weren't THERE.             http://bash.org/?255991

Re: Acting on dropped/timed-out connections

From
"Milen A. Radev"
Date:
On 08/09/05, Roman Neuhauser <neuhauser@sigpipe.cz> wrote:
> # mradev@gmail.com / 2005-09-08 11:31:25 +0300:
> > We have a daemon programme that acts as a pgsql client. It writes in a
> > DB the status of its own clients. And we have a different daemon that
> > needs to read that status information and decide upon it. The problem
> > is that the first daemon is a little fragile and from time to time it
> > crashes. I need to be able to monitor its connection to the PgSQL and
> > if it drops (times-out) to mark the status of all of its clients as
> > "unavailable" or "unknown".
>
>     Do you prefer knowing that the daemon failed, or having it
>     automaticly restarted the very same moment it crashes? If the
>     latter, take a look at djb's daemontools, or one of its open source
>     lookalikes (http://smarden.org/runit/,
>     http://offog.org/code/freedt.html).
>

It's the former - in this case I'm not responsible (read "I don't
care") about the daemon. I care about the (reasonable) veracity of the
data in the DB.


--
Milen A. Radev