Am 30.01.2012 09:24, schrieb Paul J Stevens:
> On 01/29/2012 10:47 PM, Reindl Harald wrote:
>> Interesting - Pauls Reply was blocked by Barracuda-Spamfirewall 
>> Seems this was only a temporary problem  Zeit: 2012-01-27 10:05:06 
>> Aktion:      Geblockt Begründung: Barracuda Reputation (213.214.111.4) 
>> Absender-IP-Adresse: dbmail01.icns.fastxs.net[213.214.111.4]
> 
> 'Reputation' based on what? RBLs are a completely failed concept imo.

on the other hand we have days with 250.000 blocked messages
from the barracuda-appliance and their blacklist and no
complaints about false-positives most of the time

>>> This will break IMAP body searches (who uses those??)
>>
>> hmm - i do :-)
> 
> What client?

thunderbird

>> what i am missing are the parameters for connection pooling the 
>> "dbmail.conf" from the last RC-sources looks like the dbmail 2.2.x
> 
> It's there alright:
> 
> # Number of database connections per threaded daemon
> # This also determines the size of the worker threadpool
> #
> #max_db_connections   = 10

oh - sorry for my bad eyes :-(

>> AFAIR pooling is only for imap currently and nor for POP3 or am i 
>> missing something here?
> 
> You are.
> 
> All 3.0 programs use libzdb for the database handling. This implies a
> connection pool.

good to hear - my last information is nearly a year old
and was FAIK the RC announcement

> All 3.0 network daemons use a non-blocking async network architecture
> for communications with clients using libevent.

cool!

> However: database queries are blocking! So when I first did the
> libevent transition I quickly ran into throughput issues caused by
> longer-running database queries. When everything is handled by one
> single thread this led to pretty poor performance when more than say
> 10 imap clients were connected.
> 
> This was solved by making the IMAP code - and only the IMAP code -
> multi-threaded. Now for IMAP a pool of worker threads is created; one
> thread for each database connection in the database pool. These
> workers pull their workload of an async message queue filled by the
> main thread which deals with all the network IO. The workers do their
> thing and pass the message back to the main thread via a separate
> message queue.

did i say i love your work often enough?

> pop3d, lmtpd and timsieved however just run one single main thread.
> pop3 queries are pretty fast, lmtp is asynchronous be nature (no
> humans waiting), and timsieve is run only infrequently, with low
> volumes and fast queries.

many thanks for all this informations!

> Admittedly if you run very heavy POP3 traffic you will have to make
> provisions if real-world testing proves throughput to be too low - for
> example startup multiple pop3d processes on different ports and run a
> load-balancer in front. If there is serious interest in better
> throughput for pop3 I may reconsider but it just didn't seem to
> warrant the investment at this time.

we are running dovecot as proxy in front of dbmail for several
reasons what should relax this

* auth-daemon for postfix-sasl/imap/pop3
* SSL encryption since only native supported with the new version
* replacement % -> @ before the real login (legacy history from EIMS mailserver)
* security at all - even if dbmail would have a security whole i guess
  it would be extremely hard to trigger it through the proxy

thank you for all this informations and this really fine
piece of software and best wishes from vienna!

-- 

Mit besten Grüßen, Reindl Harald
the lounge interactive design GmbH
A-1060 Vienna, Hofmühlgasse 17
CTO / software-development / cms-solutions
p: +43 (1) 595 3999 33, m: +43 (676) 40 221 40
icq: 154546673, http://www.thelounge.net/

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