Patrik Rak:
> On 15.5.2013 20:30, Wietse Venema wrote:
>
> > Patrik appears to have a source of mail that will never be delivered.
> > He does not want to run a huge number of daemons; that is just
> > wasteful. Knowing that some mail will never clear the queue, he just
> > doesn't want such mail to bog down other deliveries.
> >
> > From that perspective, the natural solution is to reserve some fraction
> > X of resources to the delivery of mail that is likely to be deliverable
> > (as a proxy: mail that is new).
>
> Very well said. Describes my thoughts exactly.
>
> So, if you don't mind, I would like to go ahead and try to implement
> this limit, for both the delivery agent slots as well as the active
> queue slots. I think that enough has been said about this to provide
> evidence that adding such knob doesn't put us in any worse position than
> we are at now, nor does it preclude us from using other solutions.
You can try. I hope you can also document the result! Neither
Victor nor I have been able to fully absorb the subtle details
of nqmgr in a reasonable time span (like a long weekend or so).
Just be aware that persistent backlog will also affect geylisted
mail, as the time to make one pass over the deferred queue increases
with backlog size. Increasing the maximal_backoff_time only delays
the onset of trouble.
> The only remaining objection seems to be the amount of back pressure
> postfix applies to incoming mail, depending on the growth of the queue.
> I believe this problem exists regardless of if this new knob is in place
> or not, so it may as well be good idea to discuss this independently if
> you feel like doing so now...
Agreed. Back-pressure to "sources outside Postfix" is orthogonal to this.
Wietse
