On Wed, 27 Feb 2013, Viktor Dukhovni wrote: > No, connection caching has nothing to do with concurrency. Whether > connections are cached, or not, Postfix will attempt parallel > delivery up to the configured concurrency limit:
Hrm. Okay, lowering default_destination_concurrency_limit is certainly a viable workaround. I’m not the Postfix expert here, and he didn’t suggest it to me. > of the MX hosts for a destination is unreachable. The load on the > remote server is identical with and without connection caching. That’s untrue because it certainly makes a difference whether you send mails in parallel or serial, especially when the receiving host then spawns an LDAP connection, a shell command and an MSA to forward the mail further. > Sendmail lacks a queue-manager, if you really want to avoid Sendmail > melt-downs under load, deploy Postfix. Sendmail does not “melt down”, it just refuses connections until the load gets lower again. I sure hope Postfix does the same if the system load is high? (The load is not necessarily from sendmail; this is a spamfilter setup which is tightly coupled to several system components, one of which is sendmail, but the LDAP search and two sed invocations as well as calling bmf are the CPU hogs here.) > Connection caching without the ability to re-use the connection in > a different delivery-agent process *is* abusive of the remote > system, since you're keeping a remote process occupied and idle, while > making new connections. This will not be implemented. You can just close them immediately if there’s no mail in the queue for the remote system any more. Or after a second. > When disgruntled, especially due to problems with system "A", don't > rant on the mailing list for system "B". My problem here is with system "B" as system "A" is working just fine and by the specs. bye, //mirabilos -- tarent solutions GmbH Rochusstraße 2-4, D-53123 Bonn • http://www.tarent.de/ Tel: +49 228 54881-393 • Fax: +49 228 54881-314 HRB 5168 (AG Bonn) • USt-ID (VAT): DE122264941 Geschäftsführer: Boris Esser, Sebastian Mancke
