An express checkout? [was: Re: Postfix and Mailscanner sitting in a tree k-iss-ing]

[Julian Field]

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paddy wrote:

>On Fri, Dec 31, 2004 at 05:33:36PM +0000, Julian Field wrote:
>
>
>>paddy wrote:
>>
>>
>>
>>>On Thu, Dec 30, 2004 at 06:00:20PM +0000, Julian Field wrote:
>>>
>>>
>>>
>>>
>>>>Incidentally, something in the same vein has already been done for
>>>>Communigate Pro, but I have never looked at that. I suspect (though
>>>>without evidence either way) that it is not approx. 100% robust in the
>>>>face of a concerted DoS attack. I go to some lengths to try to ensure
>>>>that, when under attack, the MTA will give out long before MailScanner
>>>>does.
>>>>
>>>>
>>>>
>>>>
>>>Looking at CriticalQueueSize I wonder if there might be some optimisation
>>>possible that prefers to processes mail that is more likely to ham by some
>>>simple criteria, a sort of express checkout.
>>>
>>>Possible devices to avoid starvation on the main queue could include
>>>running
>>>a slow queue along side the fast queue, so that the system is always
>>>progressing,
>>>and/or an elevator algorithm.
>>>
>>>
>>>
>>>
>>Either you appear to have changed the subject without changing the
>>Subject: or else I don't understand the link between the quoted text and
>>your reply...
>>
>>
>
>Okay, I confess it was a bit of a leap ... :)
>
>I started from 'in the face of a concerted DoS attack'.
>
>I've seen peaks of up to 500+ messages queued, which can take some time
>(on a tiny, underpowered, overloaded system) to clear up.  At times like
>that I find myself doing stuff like
>
>tail -f maillog | grep delay | sed 's/\(...............\).*\]: \([^:]*\):.* delay=\([^,]*\),.*/\1 \2 \3/'
>
>and trying not to worry about it!
>
>(or maybe that should be xdelay, I don't know!)
>
>But its not a feature request, more of a 'what do you think?'
>
>So, yes, this no longer bears any relation to the previous Subject, sorry!
>
>
What does your sed command actually do? And what would your quick
"likely to be ham" test do?

--
Julian Field
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