Re: [exim] 4096 connection barrier

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Author: Graeme Fowler
Date:  
To: exim-users
Subject: Re: [exim] 4096 connection barrier
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?

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?

Graeme