exim FUD :-) (j/k) walaupun saya sadar, perbedaan terminologi bisa menyesatkan, tapi ada beberapa point yang disampaikan cukup menarik soal 'stackless' he..he..
Salam, P.Y. Adi Prasaja ----- Forwarded message from Theo Schlossnagle <[EMAIL PROTECTED]> ----- Date: Sun, 12 Jan 2003 15:57:59 -0500 From: Theo Schlossnagle <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] Cc: Theo Schlossnagle <[EMAIL PROTECTED]> Subject: Re: Building fast email boxes I know this reply is very latent... but I didn't see a reply at all, so I thought I would add some info. On Thursday, Dec 5, 2002, at 05:07 US/Eastern, Matt Sergeant wrote: >OK, I didn't realise that exim forked a lot. I was under the >impression that it was threaded for some reason. Perhaps that's >postfix... Nope. Exim, Postfix, Qmail, sendmail, etc. all use a multiprocess model for sending mail AFAIK. All of them are capable of sending more than one message in the same process, but not concurrently. So, in Exim at least, a queu runner starts and picks up a message deliveres it, then picks up another and delivers, and again and again. So, if you want to do 120 concurrent deliveries, you need 120 concurrently running queue runners. Linux doesn't seem to have much of a problem running 500 or so Exim processes. We have set up an installation at a client that runs Exim for subscriber mail delivery of time-sensitive materials. We are able to achieve and average of 30 message/second outbound. >So is there *any* mail server out there designed for large numbers of >outgoing connections? The ironport box we have says it can handle >10,000 outgoing connections at a time (qmail can do 120 by default), >and it does this using async IO. I want to work with something that >can achieve maybe 5000 concurrent outgoing connections, and >efficiently multiplex between them (I know this can be done with >/dev/poll for example). No open source ones that I know of. OmniTI (my company) uses an in-house SMTP server that uses a hybrid multithread/multiplex approach (using /dev/poll or kqueue or whatever is best on the host OS). Our implementation appears to compete fairly well with the Ironport benchmarks. I think the Ironport product has a good place in the market. I have never used one, but all the information on their site would lead me to want to test one along side comparable solutions if I had an underachieving outbound email architecture on my hands. The Ironport design (which I think is in no way revolutionary) is a correct approach to the high capacity outbound content problem. Ironport uses something called "stackless threads" (TM). I am not sure what that is. I took (and taught) operating systems and threads are defined by two things. (1) a separate execution path and (2) a separate stack from which to operate. "stackless threads" (TM) are kind of an oxymoron as I see it. It sounds much more like an event based system where all calls are non-blocking and is multi-processor capable. Our in-house MTA is like that... I call it a hybrid thread-event model -- just like the slew of other applications that have been written in the same fashion over the last 10 years. I am not an expert on the Ironport systems at all. I have only read the information available on their site. I don't believe their product is revolutionary as their benchmarks aren't overly impressive. With that said, they beat the pants of Exim/Sendmail/Qmail/Postfix -- as they should :-) The downside as I see it, is that the Ironport is a blackbox. I would like a piece of software I can install on my FreeBSD/Linux/Solaris box. It is definitely possible to match or beat the Ironport benchmarks on a out-of-the-box untuned UNIX box. I also have no idea how much an Ironport than can send 1 million message per hour would cost. But I would wager it would be mighty pricey. If someone knows, would like to share and would not be violating any agreement, I would love to know the price points on the Ironport product line. >So that probably scratches exim from the list. I like Exim a lot. I personally prefer it (from a code elegance and usability standpoint) over other like alternatives (qmail/postfix/etc.). I find that a motivated sysadmin can make each perform pretty well. I don't know of anyone who sends more than 50 messages/second sustained (single recipient mails of course) out of a single machine with any of those products (50 is the highest I ever managed to get exim to go out of a commodity (<$3k US) machine and that was for only like a 2 hour burst). Every mail install I have runs Exim except for the custom installs we use for large subscriber list mailings. -- Theo Schlossnagle Principal Consultant OmniTI Computer Consulting, Inc. -- http://www.omniti.com/ Phone: +1 410 872 4910 x201 Fax: +1 410 872 4911 1024D/82844984/95FD 30F1 489E 4613 F22E 491A 7E88 364C 8284 4984 2047R/33131B65/71 F7 95 64 49 76 5D BA 3D 90 B9 9F BE 27 24 E7 ----- End forwarded message ----- -- Right or wrong my list. Unsubscribe option is currently unavailable. Indeed, it's available upon request .. but: cepek dulu donk!
