> On Oct 29, 2017, at 9:40 PM, J Doe <[email protected]> wrote:
>
> I had a question regarding the main.cf parameter
> “default_destination_concurrency_limit”. The man page (man 5 postconf),
> states it is: “The default maximal number of parallel deliveries to the same
> destination.”
Correct.
> and that this applies to the smtp(8) delivery agent.
It states no such thing, and indeed this is not the case.
> This got me wondering . . . how would one adjust this parameter ? I am
> thinking it is only
> through benchmarking trial and error, as a number of factors would seem to
> affect this
> (server load, bandwidth, etc.). But then I was thinking if it was through
> trial and error,
> how was the value of “20” determined when most people running Postfix will
> have varying
> equipment for their server? [1]
This parameter much less about your server's capacity that it is about
not overwhelming remote servers with too many parallel connections.
It should, for a transport that handles deliveries to many destinations,
of course not consume the entire transport process limit, which as
specified with default_process_limit or the corresponding master.cf
entry. The latter defaults to 100, so 20 is a reasonable fraction
that does not result in any single destination hogging all the
transport slots.
--
Viktor.
