mbhangui at gmail
Feb 5, 2010, 7:48 PM
Post #2 of 2
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On Wed, 2010-02-03 at 01:06 +0200, Ibrahim Harrani wrote:
> Postfix accepts mails in smtp level very fast. It can accept more than
> 1000 connections without increasing server load.
> (the reason:it is because of single processes with multi-threaded
> support and it uses FreeBSD kqueue and Linux epoll to
> handle sockets)
> But when the numbers of mail in postfix queue increase delivery of
> mail is getting slow.
>
> In qmail case, it the concurrent connection is more than 400, the
> server load increases dramatically(more than 50)
> (the reason: it forks a qmail-smtpd binary of the every connection.
> the qmail-smtpd read many control files. tcpserver uses traditional
> select() for the sockets )
>
> But qmail deliverys mail in the queue very fast.
>
> If my assumtions are correct, designing postfix style smtpd and qmail
> style mail delivery mechanism will boost the performance of mail
> system. OpenBSD's smtpd might be good start?
>
> Any comment?
I have used a different approach to increase qmail's throughput. In
fact, I have replaced all my email marketing servers which were earlier
running postfix with qmail. The trick I use is to create multiple queues
using queue-fix and running qmail-send / qmail-todo on each of the
queues. A qmail-queue wrapper called qmail-multi evenly distributes
incoming mails across each of the queues
http://en.wikipedia.org/wiki/File:Indimail_queue.png
Patch for qmail which incorporates the above architecture is in the
Patches subdirectory at
https://sourceforge.net/projects/indimail/files/
The patch removes all hard coded directories
like /var/qmail, /var/qmail/queue, etc and uses environment variables
like QMAILDIR, QUEUEDIR, etc.
I am toying with the idea of moving all stuff (in qmail-smtpd) like
loading all the control files to a separate process so that qmail-smtpd
does only SMTP. All other stuff like badmailfrom, rcpt checks, etc move
out to a daemon. However, I am not sure of the performance gain that i
will get and also the fact that there will be some penalty due to the
added interprocess communication between qmail-smtpd and the daemon.
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