[Dovecot] Re: Dovecot memory use and settings

[Roger Weeks]

On Jan 14, 2006, at 12:40 AM, Tomi Hakala wrote:

>> Even on really busy servers, I never see more than three auth- 
>> worker processes on either of our servers.  The dovecot.conf has  
>> this:
>> auth_worker_max_count = 150
>> But I don't see anywhere I can tell it a minimum number of auth  
>> worker processes to start when dovecot starts.  Is there an  
>> auth_worker_min_count or something similar?
>
> There is no such option, more workers are spawned automatically if
> all current workers are busy.

Actually, it seems to depend on your type of authentication.  Digging  
through dovecot.conf yesterday, I finally found this:

   # SQL database
   userdb sql {
     args = /usr/local/etc/dovecot-sql.conf
   }

   # Number of authentication processes to create
   #count = 1

I have changed this to count=20 on my servers and since then I have  
not experienced any out of memory issues with auth-workers or the  
MySQL client.

Leaving this at the default of 1 for authentication against MySQL  
does not work for servers with lots of clients.  20 may be too high -  
but I'd rather err on the side of not having 2 minutes of refused  
authentication while auth-workers restart.

I might suggest that this default be changed to something other than  
1.  With the default settings in the conf file, using MySQL  
authentication, no more than a maximum of 3 auth-worker processes are  
ever created.

Roger Weeks