[Mimedefang] ALLOW_NEW_CONNECTIONS_TO_QUEUE behavior
dfs at roaringpenguin.com
Sun Aug 27 18:12:28 EDT 2017
On Sat, 26 Aug 2017 22:52:15 -0700
Amit Gupta <amit777 at gmail.com> wrote:
> Assume a burst of emails comes in and all 20 md processes are busy
> 1) What should the 21st and higher connecting clients
Sendmail will appear to respond more slowly than usual.
> 2) Is there a configurable limit to the number of queued
Yep. The "-q" option to mimedefang-multiplexor. See the -q and -Q
command-line options in the mimedefang-multiplexor(8) man page.
> 3) What's the downside of letting the connections queue
> other than holding open more TCP connections?
Holding open more connections and using more milter threads.
> 4) Any other tips on the settings you use in production?
If you actually need to queue requests more than occasionally, you
need a more powerful server. The queueing feature is supposed to handle
transient bursts of traffic. It isn't meant to squeeze more steady-state
performance out of a server.
> The reason I'm asking is because we recently had a burst of traffic
> that caused the IO on our server to go up to a point where everything
> became unresponsive for a couple minutes. We had our MX_MAXIMUM set
> to 110.
How much RAM did you have? You really, really, really don't want a
MIMEDefang scanning server to start swapping.
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