-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Sep 27, 2006, at 10:36 PM, Brad Knowles wrote:
> At 6:33 PM -0700 9/27/06, Carson Gaspar wrote: > >> I love the idea. A fork/exec per message always makes me >> twitch... I have a >> feeling it would also provide better fault-tolerance, especially >> in a >> replicated filesystem cluster, where you have clear atomic >> behaviour at >> your disposal. > > I agree that fork()/exec() is not an ideal model here, but then > postfix doesn't use that model internally -- it uses a single parent > with multiple child processes, and then hands off sockets. It also > keeps pretty much the entire working queue in memory, as opposed to > single-threading through the filesystem. > > I don't see how using Maildir is going to solve any of these > problems. IMO, if we're going to learn from postfix, I think we > should learn the right things and take away the right lessons, and > not just glom onto some alternative technique that has been known to > have a whole host of other problems. Remember that we're only talking about how to most efficiently get mail from the MTA via local delivery into the Mailman incoming queue. Once in Mailman we'll handle the message our own way, not with maildir. This means that we're limited by what the various MTAs we want to integrate with support. Until now, we've always gone with delivery to a program, because that's supported by all MTAs. This is what Carson was referring to by fork/exec -- the MTA must fork/exec Mailman's mail wrapper (i.e. post) which basically just sucks the message text from stdin and write it to a file. It seems clear that if you could eliminate that extra process (essentially a glorified cat), you'd get a win. I think you're going to get about the same amount of filesystem thrashing in either case, so you might as well avoid the extra process overhead. Looking at Postfix, what other options are readily available? I suppose you could try to hook into the transport maps, but if I understand them correctly, you're still talking about forking a process per message. Maybe LMTP to a daemon process is another option, but there appears to be no documentation on www.postfix.org about LMTP. As for what's best for other MTAs, that's a good question. I think we'll always have to support delivery-to-program since that seems like it's the lowest common method. If there are delivery mechanisms that make more sense for specific MTAs, then I'm all for including them, but others who are more familiar with those mailer servers will have to help (read: donate code). - -Barry -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (Darwin) iQCVAwUBRRtHdnEjvBPtnXfVAQIVKQP+PBYbnBeG7M7MySaZdGyUy74d/cRwModC p19xJNMDsSvKKR4dy+uWzyzTF9uM3xPSKQUokvMWQHudyMmtf980E6db4THF1/do i87z/B3gLS+7SwyXYeRPqnMlEjuHkmFGjPS4t9jz9sGaraixVE9qMqJ3F8S+n7hi 6DuAdUtRqOw= =s19m -----END PGP SIGNATURE----- _______________________________________________ Mailman-Developers mailing list Mailman-Developers@python.org http://mail.python.org/mailman/listinfo/mailman-developers Mailman FAQ: http://www.python.org/cgi-bin/faqw-mm.py Searchable Archives: http://www.mail-archive.com/mailman-developers%40python.org/ Unsubscribe: http://mail.python.org/mailman/options/mailman-developers/archive%40jab.org Security Policy: http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq01.027.htp
