[Dovecot] dovecot-auth stops responding

[Nathan M]

On Thu, Sep 10, 2009 at 11:43 AM, Timo Sirainen <tss at iki.fi> wrote:
> On Thu, 2009-09-10 at 14:32 -0400, Jonathan Siegle wrote:
>> It only helps when I kill dovecot-auth, not dovecot-auth -w.
>
> Interesting..
>
>> > What if you kill imap-login processes instead?
>> >
>>
>> I don't have imap-login processes associated with inetd spawned
>> dovecot.
>
> Why do you use inetd? I'm currently wondering if I should bother adding
> inetd support to Dovecot v2.0.
>
>> Yes I have truss. So tomorrow when this happens I'll do truss -f -p on
>> the dovecot-auth process?
>
> Yes. Also having auth_debug=yes enabled might show something useful.
> What does it log last before it stops responding?
>

I've run across what seems to be the same issue with 1.2.4.  I
upgraded from a 1.0 release which was not having any issues; however,
I'm very afraid to revert because the server gets killed if it has to
rebuild caches/indexes.  I don't have this issue on lesser loaded
1.2.4 installations, only this server which handles roughly 6000
mailboxes and maintains a higher overall load.

The difference is we aren't doing PAM, we have it disabled.  We do SQL
authentication only.  Exact same symptoms, the server and all active
connections remain online; however, new connections coming in via
POP3/IMAP hang.  The connection is made, but the banner is never
shown.

The log, with auth_debug enabled doesn't seem to show anything useful,
it only shows a ton of connections being dropped for remaining idle
for too long when this begins happening.  ie.  POP3/IMAP clients are
connecting, never getting a banner, and therefore never sending login
credentials, then dovecot drops the connection eventually.

System affected is linux 2.6.18 (centos 5.2).  Any help diagnosing and
fixing this would be greatly appreciated.  I'm not sure where to go
from here.

- N