On 29 Oct 2013, at 17:17, Viktor Dukhovni <[email protected]> wrote:
> On Tue, Oct 29, 2013 at 05:01:05PM +0000, Jeremy Harris wrote: > >> On 29/10/13 16:19, Osborne, Paul ([email protected]) wrote: >>> I have checked through the manual for the version we are running 4.72 >>> (Debian - squeeze) and cannot see an option like: >>> >>> smtp_queue_size_backoff >>> >>> Where Exim does not respond to SMTP if there are X no of mails in its own >>> queue waiting to be processed. >>> >>> Is there such an option, if so what is it? If there is not can I add it >>> as a feature request? :) >> >> RFEs can always be opened at http://bugs.exim.org/ >> For your immediate needs, I'd suggest putting some custom stuff onto >> your smtp connect ACL, involving a ${run } expansion to evaluate >> the queue size. > > With a cache of the count that is updated periodically, rather than > every time it is queried. Scanning the queue counting messages > can be I/O intensive. On my machines, `ls /var/spool/exim/input |wc -l` is about an order of magnitude faster than `exiqgrep -c`. The latter takes about half a second for a queue of 1000 or so items. Of course, `ls` reports double the number, since there are two files for every queued item. % time exiqgrep -c 1259 matches out of 1259 messages real 0m4.625s user 0m0.160s sys 0m0.186s % time ls input/ |wc -l 3020 real 0m0.647s user 0m0.006s sys 0m0.043s > You don't want to do that on every incoming > SMTP request. You probably also want a high/low watermark strategy > so that once the count exceeds the high mark, the throttling > continues until it drops below the low mark. > > Such back-pressure tuning can be tricky. The queue can be large > in steady state with deferred mail to a destination that is down, > while other destinations are just fine, and you may not want to > stop accepting mail generally. When all mail is queued for the > same resource (e.g. waiting to be scanned), that's a more easy case > to deal with. > > -- > Viktor. > > -- > ## List details at https://lists.exim.org/mailman/listinfo/exim-users > ## Exim details at http://www.exim.org/ > ## Please use the Wiki with this list - http://wiki.exim.org/ -- Ian Eiloart Postmaster, University of Sussex +44 (0) 1273 87-3148 -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
