On 06.05.2014 14:14, Timo Sirainen wrote:
On 5.5.2014, at 23.13, Jochen Bern <Jochen.Bern@LINworks.de> wrote:
The problem I'ld like to ask for help with here is that dovecot's imap-login process doesn't terminate when the FIN is received, or when the IMAP protocol's inactivity timeout is reached, it takes *more than two hours* for it to go away. Because of that, this single client racks up 1100+ processes (counting against dovecot's configured limits), TCP connections, and the associated RAM usage. .. dovenull 12064 0.0 0.0 42440 3656 ? S 19:32 0:00 \_ dovecot/imap-login [1 connections (1 TLS)]
The process is taking 0% CPU?
Less than 0.002%, in any case.
There was bug where a broken handshake could have caused 100% CPU usage. Maybe the same problem could happen in a slightly different way and also not cause CPU usage. http://hg.dovecot.org/dovecot-2.2/rev/c0236d1c4a04 fixes this.
Although even then .. I'm not sure why the process wouldn't die sooner. And Dovecot especially should kill old imap-login processes that haven't logged in if it reaches the imap-login process limit.
I'd anyway try v2.2 first..
Thanks for the pointers. We're having a change management and an official-repos-if-at-all-possible policy going on, so I'll likely start with adding just this patch and (belt and suspenders ;-) a bit of "iptables -m connlimit" in the upcoming maintenance windows.
Watching the production server run up to the limits hoping that they'll prove to be padded walls *this* time (rather than raising malfunction alerts in hundreds of client sites as usual) takes a braver man than myself, I'm afraid ... :-}
Kind regards, J. Bern
*NEU* - NEC IT-Infrastruktur-Produkte im <http://www.linworks-shop.de/>: Server--Storage--Virtualisierung--Management SW--Passion for Performance Jochen Bern, Systemingenieur --- LINworks GmbH <http://www.LINworks.de/> Postfach 100121, 64201 Darmstadt | Robert-Koch-Str. 9, 64331 Weiterstadt PGP (1024D/4096g) FP = D18B 41B1 16C0 11BA 7F8C DCF7 E1D5 FAF4 444E 1C27 Tel. +49 6151 9067-231, Zentr. -0, Fax -299 - Amtsg. Darmstadt HRB 85202 Unternehmenssitz Weiterstadt, Geschäftsführer Metin Dogan, Oliver Michel