W3C home > Mailing lists > Public > www-email-discuss@w3.org > March 1999

Re: KEEPING SERVER LOAD AVERAGES DOWN

From: ONIME EHIMIKA OHIREIME <onime@ictp.trieste.it>
Date: Tue, 16 Mar 1999 13:54:24 +0100 (MET)
To: Steve Song <ssong@idrc.ca>
cc: www4mail-comments@w3.org
Message-ID: <Pine.GSO.3.96.990316131256.7132A-100000@sv4>

On Mon, 15 Mar 1999, Steve Song wrote:

> Hi Clement,
> 
> My concern in the scenario you propose is that the demand will still be out
> there on the net waiting.  You are not addressing the demand, just the rate
> at which you deal with it.  
>

Well Steve,
The demand will always be out there except when the users are
asleep, the idea here is to spread out the processing to a rate that
your server will be able to cope with.

As I propose most www4mail processes currently running simply sleep
(some will also exit) when the load average is very high until the load
average comes down. new processes however will exit with a request to
sendmail to retry.

Addressing the demand means cutting down the number of users
or requests to your server. www4mail already provides for this through the
conf/.access and conf/.deny files, with these two files you can restrict
access to your server, example to mails from your domain. www4mail will
not bother to answer or reply anyone who does not belong in the list.

 
> When server load gets too high, I want to stop receiving www4mail requests
> but I still want to receive other mail.   If it were possible, when server
> load is over a given point, for Sendmail to respond with an error message
> (similar to JUNK mail filtering) saying "Sorry www4mail server too busy,
> please try again later" but only for www4mail requests.  Otherwise, the

With the proposed mechanism, your server can still receive mails when the
load is high, however when it starts up a www4mail process, it will exit
with a temporary failure code, it is possible to change this to a service
Unavailable code but this means that the end user will label your
server/service as un-reliable.


> mail request will still be out there and will retry and retry.   Could a
> rule to do something like that could be hacked together?  Certainly,
> Sendmail can detect server load and it can also do spam rejections based on
> Email addresses.  Now, if only there were some way to put them together.
> 
You can change the error code returned to Sendmail (via a configuration
file directive) and Sendmail will send a mail to the user saying Service
Unavailable. However, you may not want to do this because of the above
consideration.

Thanks
Clement
Received on Tuesday, 16 March 1999 08:00:58 UTC

This archive was generated by hypermail 2.4.0 : Friday, 25 March 2022 10:09:29 UTC