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On Thu, 20 Jan 2000, Anand Buddhdev wrote:
> Is there any plan to add such code in? At least 3 well-known MTA's
> support pipelining in the SMTP server (qmail, exim, postfix), but
> only postfix and serialmail use it in their SMTP client, and so
> the majority of SMTP transactions don't make use of this timesaving
> feature.
how much time does this actually save??
I guess it may cut down overall latency, although cost a bit of CPU...
theos@??? said:
> I agree completely. In fact, this would not be that difficult in the
> current architecture if you use a connection caching process. You
> could steal most of the code from mod_backhand (http://
> www.backhand.org/mod_backhand/). It has one process that maintains
> open connections and the clients (Apache children in mod_backhand's
> case, but exim delivery processes in this context) would request an
> open file descriptor to machine X. If the connection caching process
> doesn't have an open file descriptor to X, then it says so and it is
> the clients job to "connect()". Once the client is finished with the
> connection, it passes it (still open) to the caching process. If the
> caching process has an open file descriptor to machine X when the
> client requests it, it simply passes it along.
connection caching/reuse is not related to ESMTP pipelining.
Exim already reuses SMTP connections for queued mail. A connection
caching engine is a needless addition of complexity and has other nasty
side effects like leaving open connections hanging around - which can
be a DoS on the receiver.
Nigel.
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[ Nigel Metheringham Nigel.Metheringham@??? ]
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