[Dovecot] Dovecot (IMAP) Hangs sometimes

[Mario Gomide]

The specific moments are at about 9:40 am and 2:30 pm. Exactly when I have
most of my users connecting simultaneously (when they arrive in the morning
and back from lunch break). At these exact moments, dovecot hangs.


Anyways, I took a look at http://wiki.dovecot.org/LoginProcess. I increased
the default login_max_processes_count from 128 to 256 and restarted dovecot.

Right before doing this (2:24pm, at this time, imap was getting slow already
and dovecot was about to hang) I checked my processes every second:
ps -ef | grep imap-login | grep dovecot | wc -l
and the results varied from 149 to 152.

After setting login_max_processes_count to 256, I hope the problem is fixed.
I didn't do anything related to open file descriptors.

Mario



On Fri, Jan 8, 2010 at 11:36 AM, Steffen Kaiser <
skdovecot at smail.inf.fh-brs.de> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
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> On Fri, 8 Jan 2010, Mario Gomide wrote:
>
>  Then I commented the listen line, and things got better, but not good
>> enough
>> yet. Strange, uh?
>>
>
> I never tried that.
>
>
>  Just for the record: My mail server is running super fast! The problem
>> happens only at specific moments, twice a day, only.
>>
>
> specific moments? Which and what are the spesifics?
>
> If I remember correctly, I made logs of the number of file descriptors of
> the "dovecot" process; each time the number _almost_ reached the max (say
> one or two  are not allocated yet), I saw the stalls _and_ when I manually
> logged off users (kill -15 imap-process) the number did not decreased. Well,
> not much anyway.
> Sort of, it looked like a fd leak.
>
> Since I have ulimit -n in my init.d, no such problem came up again. The
> previous ulimit was lower than the max Dovecot could handle.
>
>
> Regards,
>
> - -- Steffen Kaiser
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