[Mimedefang] Playing with -X and -P for Ticks

[Kevin A. McGrail]

On 10/22/2012 4:41 PM, David F. Skoll wrote:
> On Mon, 22 Oct 2012 16:32:24 -0400
> "Kevin A. McGrail" <KMcGrail at pccc.com> wrote:
>
>> Anyone have any guidance on settings for -P and -X in order to
>> maintain persistent DB connections?
> Yeah, don't.  Because it won't work (as you no doubt discovered. :))

Thanks David.  In a way, this was more helpful than you might imagine 
because my analysis was leading towards certain slaves never running 
ticks but this makes it definitive without me researching.

> The logical place to do that
> would be right at the beginning of filter_sender, filter_recipient,
> filter_begin, etc.... whichever callbacks you care about.

For me, at least, with a 0.33% failure rate being rather low, rather 
than adding ping a whole bunch of times at each callback that might use 
a DB call, I've changed my centralized query function to try connecting 
if the query fails with what looks like a timeout failure.  I also added 
some logic so it tries only one more time.

Beyond that, I haven't figured out why I think this is more elegant than 
your logic, though so any input greatly appreciated.

Overall though, knowing that this "bandaid" is needed because you can't 
really guarantee a tick will maintain a persistent DB connection makes 
me feel a lot better about using such a bandaid.

> (Also, SQL client timeouts are totally evil.  Don't use them.  If your
> DB can't handle lots of connections, use a connection pooler.)
Thanks.  That makes sense.

Regards,
KAM