Re: [exim] Exim has a bad queue handling?

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Author: Philip Hazel
Date:  
To: Dave Lugo
CC: exim-users
Subject: Re: [exim] Exim has a bad queue handling?
On Mon, 23 Oct 2006, Dave Lugo wrote:

> (wild off the cuff stuff that I don't know enough
> about filesystems to say if this would improve stuff)
>
> If exim has to look at the file to see if a new
> delivery attempt is due, would it be faster overall
> (for queue ops) to instead reflect that information
> in the -H filename, and just have exim update that as
> needed?


Impossible. Remember that a message may have multiple recipients, and
each recipient domain may resolve to multiple IP addresses. Exim looks
at the file to get the list of recipients; it then uses the routers to
find the list of IP addresses for each recipient; it then looks in its
hints database for retry information for each IP address (and
IP/recipient combinations for recipient errors). The amount of
potential information is therefore rather more than one could sensibly
put into a file name.

Furthermore, even if it were only one recipient and one IP address, the
next delivery due time is not fixed to a message. Consider the common
"connection failed" case (a host error). If there are 10 messages
waiting for one host, one delivery is tried when the retry time has
passed; if that fails, the other 9 messages are not tried at that time.
(It would be pretty pointless, wouldn't it?)

-- 
Philip Hazel            University of Cambridge Computing Service
Get the Exim 4 book:    http://www.uit.co.uk/exim-book