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@smail.inf.fh-brs.de> wrote:
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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,
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