[OT] Re: [ADMIN] List mods

On Thu, 18 Feb 1999 13:40:48 +0000 (GMT), Thomas Anderson writes:
>On Wed, 17 Feb 1999, Matthew Seidl wrote:
>
>> I'm trying out a modification to majordomo that should improve list
>> performance.  The goal is to reduce the turn arround time of
messages,
>> i.e. the time from the system getting a message to it attpeting to
>> deliver it to everyone on the list should be reduced.
>
>well, i should imagine that most of the latency on the list is due to
the
>time taken for the mails to cross the space between berkeley and the
>listizen. unless you're doing something really clever, surely
>modifications to majordomo are of minor importance?
>

Not really.

Long winded and technical discussion of latency in an email environment
coming up.  Please delete if the thought of geeking about email
doesn't thrill you to the bone.

In a straight up majordomo environment, majordomo does all the funky
list bits, then effectively hands the message to sendmail with a long
list of people to deliver it to.  Sendmail does some sorting on this
list, but not alot.  It then starts trying to deliver the email to the
first person, then the next, etc.

This means that if you're at the bottom of the list, it could be quite
some time before it even tries to deliver to you.  Depending on how
many people above you there are, and the timeouts taken for
unresponsive sites.

The modification that just went into effect splits this big group of
names into lots of smaller groups, and sorts by domain, before handing
it off to sendmail.  This means everyone at yahoo.com for example gets
delivered in one batch for example.  And the longest you have to wait
is the length of one of these smaller chunks.  The possible
disadvantages to doing this are increased load spikes on the mailing
list machine as it tries to deliver everything in parallel.  But,
since most of the deliveries should be quick, overall it may lower the
load as only a few sendmail's hang on delivering slow email, instead
of most of them.

This really points out the two kinds of delay.	There's the delay in
seeing your own messages echo'd back from the list.  This is purely a
your local system, i.e. how long does it take mail to get to you.
Then there's a problem of seeing replies to your message before
getting the message back.  This shows that you are really far down on
the list, as before the message tries to get to you, its been received
by others and responded to.  The goal is to reduce the turn time to
you by enough that this won't happen.

Not real exact I know, but I don't want to get into total specifics
unless there's a sendmail guru on the list who wants to debate these
things. :)

-=- Matthew L. Seidl		email: seidl@cs.colorado.edu		
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