Re: [exim] 4096 connection barrier

--On 23 February 2009 12:13:07 +0000 Graeme Fowler <graeme@???>
wrote:

> On Mon, 2009-02-23 at 11:45 +0000, Ian Eiloart wrote:
>> So, Exim's limit isn't reached on my machines, but nevertheless the
>> limit needs revisiting for those who don't have my problem. Marc's
>> right. The limit is too low for modern hardware.
>
> ...to which the followup question is: what is a suitable limit for
> modern hardware and OS combinations?
>
> To expand a little on your OSX limits, should Exim be checking on OSX
> that it never spawns more than 2499 processes (queue runners, delivery
> processes, inbound handlers and so on)? Should it factor OS variations
> at all, or should they simply be documented?

It's not necessary to place a limit in OSX. I can do that with launchd
limits. What I set it to will depend on the other things that I'm using the
server for.

> What should be done to compare, say, Postfix / Sendmail et al?
>
> Most of these are (IMO) fairly rhetorical questions based on the fact
> that the following one-line change moves the goalposts:
>
> --- daemon.c.orig 2009-02-23 12:08:25.000000000 +0000
> +++ daemon.c 2009-02-23 12:08:40.000000000 +0000
> @@ -1199,3 +1199,3 @@
>
> - if (smtp_accept_max > 4095) smtp_accept_max = 4096;
> + if (smtp_accept_max > 16383) smtp_accept_max = 16384;
>
> But the first question stands: what value should be chosen? Or should
> there simply *not be* an upper limit, so people can skewer themselves if
> they choose an insane value for smtp_accept_max?

Well, I already can launch enough SMTP processes to hose my server,
unfortunately! I don't see why there should be a limit, but there should be
a sensible value in the default config file, and a note to caution that
Exim will launch up to smtp_accept_max processes.

> Graeme



--
Ian Eiloart
IT Services, University of Sussex
x3148