[Dovecot] locking problem

[myron]

On Feb 1, 2012, at 4:11 PM, Timo Sirainen wrote:

> On 1.2.2012, at 22.43, myron wrote:
>
>>>> dovecot: IMAP(<user>): Timeout while waiting for lock for  
>>>> transaction log file /users/<user>/mail/.imap/INBOX/ 
>>>> dovecot.index.log
>>> How large is the /var/mail/<user> mbox file?
>>
>>
>> -rw------- 1 <user> mail 15M 2012-02-01 14:46 /var/mail/<user>
>
> OK, so not very big.

His isn't, but I have users with 500MB to a GB mailbox. Could they be  
the cause of the problem?

>
>> Can I just zero out the 3 files in that directory.
>>
>> 6240 Jan 31 13:26 dovecot.index
>> 165888 Jan 31 14:39 dovecot.index.cache
>> 25100 Jan 31 14:42 dovecot.index.log
>
> You can delete them, but somehow I doubt that helps.. That error  
> message anyway happens when a session has opened the mbox and is  
> "syncing" it. This normally is a pretty fast operation, but the  
> error message indicates that another session saw the first session  
> doing it for over 3 minutes until it aborted.
>
> Do you have hanging imap processes eating 100% CPU?

Hardly anything:
ps -eo pcpu,pid,user,args | sort -k 1 -r | head -20
%CPU   PID USER     COMMAND
  0.0     9 root     [events/0]
  0.0   993 root     /usr/sbin/sshd -D
  0.0   984 root     /usr/sbin/cupsd -C /etc/cups/cupsd.conf
  0.0  9677 <different user>     imap
  0.0  9659 dovecot  imap-login
  0.0   959 root     [ext4-dio-unwrit]
  0.0   958 root     [ext4-dio-unwrit]
  0.0   957 root     [jbd2/dm-1-8]
  0.0  9442 root     [lockd]
  0.0   939 root     [ext4-dio-unwrit]
  0.0   938 root     [ext4-dio-unwrit]
  0.0   937 root     [jbd2/dm-3-8]
  0.0   930 root     [ext4-dio-unwrit]
  0.0   929 root     [ext4-dio-unwrit]
  0.0   928 root     [jbd2/dm-2-8]
  0.0  9192 root     /usr/sbin/apache2 -k start
  0.0   911 root     [ext4-dio-unwrit]
  0.0   910 root     [ext4-dio-unwrit]
  0.0    90 root     [kconservative/1]

> That could explain it if Dovecot doesn't like something in the mbox  
> file. Also there may have been some other reasons for this that are  
> already fixed in newer versions.

I looked at the upgrade list on the server and dovecot isn't showing  
any upgrades via atp-get