dovecot - Dec 2013 - auth failures

Hello,

last week and today our dovecot pop3 server stopped responding.
Without any other logentries dovecot start to log only this:

Dec 12 09:14:12 mbox1 dovecot: auth: Error:
ldap(testuser,192.0.2.110,<FBZH7lHtAQAK/FCj>):
ldap_search(base=ou=accounts,dc=example,dc=de
filter=(&(|(uid=testuser)(mail=testuser))(!(state=blocked)))) failed:
Operations error

For every pop3 Session, ~2000 per Minute ..., over 10 Minutes
I send dovecot a SIGTERM. After dovecot was started again, all was fine again.

# doveconf -n
http://postmaster.datev.de/tmp/dovecot.conf

The LDAP-Server itself did resond to queries in the same timeframe. I know this
because the MTA on the same host was able to deliver messages into mailboxes.

Any hints?

Thanks
Andreas

-- 
Andreas Schulze
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On 12.12.2013, at 13.05, Andreas Schulze <andreas.schulze at datev.de>
wrote:
> last week and today our dovecot pop3 server stopped responding.
> Without any other logentries dovecot start to log only this:
> 
> Dec 12 09:14:12 mbox1 dovecot: auth: Error:
ldap(testuser,192.0.2.110,<FBZH7lHtAQAK/FCj>):
ldap_search(base=ou=accounts,dc=example,dc=de
filter=(&(|(uid=testuser)(mail=testuser))(!(state=blocked)))) failed:
Operations error
> 
> For every pop3 Session, ~2000 per Minute ..., over 10 Minutes
> I send dovecot a SIGTERM. After dovecot was started again, all was fine
again.
> 
> # doveconf -n
> http://postmaster.datev.de/tmp/dovecot.conf
> 
> The LDAP-Server itself did resond to queries in the same timeframe. I know
this because the MTA on the same host was able to deliver messages into
mailboxes.
Likely the difference is that Dovecot keeps the LDAP connection open for a very
long time, while MTA likely recreates new connections often (maybe even every
time). I guess the fix would be to simply treat that error as "reconnection
required": http://hg.dovecot.org/dovecot-2.2/rev/ea38559ffd4e