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

Re: KEEPING SERVER LOAD AVERAGES DOWN

From: Steve Song <ssong@idrc.ca>
Date: Tue, 16 Mar 1999 18:59:17 -0500
Message-Id: <4.1.19990316183206.00a4d540@internet.idrc.ca>
To: www4mail-comments@w3.org
Hi Clement,

I accept your argument  ;-)  (although I am not sure I understand how it
will not result in spiralling mail queues) and I look forward to testing it
out.

Cheers... Steve.

At 08:26 AM 99/03/16 , onime@ictp.trieste.it wrote:
>
>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 18:59:16 UTC

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