[Dovecot] [sfs: dovecot-auth file descriptor usage]
I am re-posting this message from last Friday, as I have seen no replies. It is critical that we address this problem, since until then we cannot put more than a few hundred users on our server.
If Dovecot-auth TRULY needs to keep open a file descriptor for every single login session, we will have to start looking at alternatives.
In short: Help!
----- Forwarded message from Steven F Siirila <sfs> -----
Date: Fri, 5 Jan 2007 13:55:38 -0600 From: Steven F Siirila <sfs> To: dovecot@dovecot.org Subject: dovecot-auth file descriptor usage User-Agent: Mutt/1.4.2.1i
In dovecot-auth (rc15) we experienced problems when the file descriptors reached 256 (due to a Solaris fdopen() call described previously). The issue was that there was one file descriptor being used for every imap-login and pop3-login process (in our environment of SSL-only that means one for every active IMAP and POP connection).
Mods were made (and appear in rc16) to close out the descriptor in question after using it during authentication (as I understand it). However, I am still seeing plenty of file descriptors left open in rc16 (one per session). For example, on a Solaris 9 server with 9 IMAP connections open here is an lsof excerpt of dovecot-auth:
dovecot-a 26071 root 7u unix 105,136 0t79 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x3000d084250) dovecot-a 26071 root 8u unix 105,140 0t80 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x3c9c4227b68) dovecot-a 26071 root 9u unix 105,149 0t79 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x3cbaa7680b8) dovecot-a 26071 root 10u unix 105,266 0t79 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x3cbaa765d48) dovecot-a 26071 root 11u unix 105,160 0t79 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x3cbaa7667e0) dovecot-a 26071 root 12u unix 105,255 0t79 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x3cbaa769288) dovecot-a 26071 root 13r DOOR 265,0 0t0 50 /var/run (swap) (door to nscd[7752]) dovecot-a 26071 root 14u unix 105,258 0t79 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x30002dc4008) dovecot-a 26071 root 15u unix 105,282 0t80 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x30003185738) dovecot-a 26071 root 16u unix 105,141 0t80 3190 /devices/pseudo/tl@0:ticots->/var/opt/dovecot/run/dovecot/login/default (0x30003185ac8)
With the modification made, shouldn't these no longer accumulate?
--
Steven F. Siirila Office: Lind Hall, Room 130B Internet Services E-mail: sfs@umn.edu Office of Information Technology Voice: (612) 626-0244 University of Minnesota Fax: (612) 626-7593
----- End forwarded message -----
--
Steven F. Siirila Office: Lind Hall, Room 130B Internet Services E-mail: sfs@umn.edu Office of Information Technology Voice: (612) 626-0244 University of Minnesota Fax: (612) 626-7593
* On 10/01/07 10:43 -0600, Steven F Siirila wrote:
| I am re-posting this message from last Friday, as I have seen no replies.
| It is critical that we address this problem, since until then we cannot
| put more than a few hundred users on our server.
I run a server with 8,000 accounts with dovecot rc15 all this time. A
few hundred is not a big number, since it's less than 1000.
| If Dovecot-auth TRULY needs to keep open a file descriptor for every single
| login session, we will have to start looking at alternatives.
Are you threatening someone?
Seriously though, there must be something very broken in your OS, I
think. I run FreeBSD 5.5-STABLE on about 40 systems, all with dovecot
rc15 and each handling at least 100 accounts (bar for my big server with
8000+) and I don't hear complains...
Why don't you start by switching OS? ;)
-Wash
http://www.netmeister.org/news/learn2quote.html
DISCLAIMER: See http://www.wananchi.com/bms/terms.php
--
+======================================================================+
|\ _,,,---,,_ | Odhiambo Washington
On Wed, Jan 10, 2007 at 10:33:19PM +0300, Odhiambo WASHINGTON wrote:
* On 10/01/07 10:43 -0600, Steven F Siirila wrote: | I am re-posting this message from last Friday, as I have seen no replies. | It is critical that we address this problem, since until then we cannot | put more than a few hundred users on our server.
I run a server with 8,000 accounts with dovecot rc15 all this time. A few hundred is not a big number, since it's less than 1000.
That was my point; we only have the ability to put a few hundred on the system, since any more than that causes us to start rejecting connections.
| If Dovecot-auth TRULY needs to keep open a file descriptor for every single | login session, we will have to start looking at alternatives.
Are you threatening someone?
No, I was thinking more along the lines of looking at different ways to solve the problem. For example, compiling in 64-bit mode gets around the Solaris limitation. Or, going away from Solaris (not really an option).
Seriously though, there must be something very broken in your OS, I think. I run FreeBSD 5.5-STABLE on about 40 systems, all with dovecot rc15 and each handling at least 100 accounts (bar for my big server with 8000+) and I don't hear complains...
Solaris 32 bit API prevents STDIO (FILE *) from referencing file descriptors greater than 255. That is because they value binary compatibility with older applications.
Why don't you start by switching OS? ;)
Not an option. Thanks for sharing your experiences; we are very interested in learning what our capacity limits might end up being BEFORE we reach them. :)
-Wash
http://www.netmeister.org/news/learn2quote.html
DISCLAIMER: See http://www.wananchi.com/bms/terms.php
-- +======================================================================+ |\ _,,,---,,_ | Odhiambo Washington
Zzz /,`.-'`' -. ;-;;,_ | Wananchi Online Ltd. www.wananchi.com |,4- ) )-,_. ,\ ( `'-'| Tel: +254 20 313985-9 +254 20 313922 '---''(_/--' `-'\_) | GSM: +254 722 743223 +254 733 744121 +======================================================================+ What sane person could live in this world and not be crazy? -- Ursula K. LeGuin
-- Steven F. Siirila Office: Lind Hall, Room 130B Internet Services E-mail: sfs@umn.edu Office of Information Technology Voice: (612) 626-0244 University of Minnesota Fax: (612) 626-7593
participants (2)
-
Odhiambo WASHINGTON
-
Steven F Siirila