Hi Viktor, > On Oct 30, 2017, at 12:11 AM, Viktor Dukhovni <postfix-us...@dukhovni.org> > 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.
Oh, perhaps I am mistaken. When I look at that parameter using: http://www.postfix.org/postconf.5.html ...it states: “This is the default limit for delivery via the lmtp(8), pipe(8), smtp(8)and virtual(8) delivery agents.” >> 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. Ah, I see. Thanks for your reply, - J
