[Dovecot] Login processes in Dovecot

[Scott Haneda]

On Jun 8, 2009, at 2:28 PM, Timo Sirainen wrote:

> On Jun 8, 2009, at 2:17 PM, Scott Haneda wrote:
>
>> Thanks, I have been looking at those adjustments.  My concern, is  
>> that if Dovecot uses a process per imap or pop connection, 2048 is  
>> not nearly enough for any significant email system.
>
> Yes, it uses a process per each logged in user. POP3 processes are  
> short living sho they shouldn't matter much, but yeah, if you have  
> lots of IMAP connections that can become a problem. But typically  
> what I've seen a single server can handle maybe 1000 simultaneous  
> connections before running out of disk I/O. So are you sure the fd  
> limit is the first problem you run into?

Just to be clear, I have not run into this problem yet, and do not  
hope to :)  Good point, there is indeed probably other overheard I  
would run into.  Apple Mail plays non friendly, and opens a ton of  
IMAP connections.  I believe, ~4 for each account, and maybe ~4 for  
each folder you are subscribed to as well.

I was simply estimating, what my upper limits are going to be.  I have  
a client who has a really busy IMAP server, one day I want to bring  
him on over to Dovecot.  At this time, just covering my bases to make  
sure I do not spend a lot of time installing and building things to  
find out there is a ceiling.

As to disk I/O, that indeed could be an issue.  I am trying to build  
out a very fast set of drives.  Most of the time, IMAP is going to be  
idle for my users, and a slow trickle of emails will be coming in on  
demand.  But that does not mean that the connections/processes are not  
going to be open.

Sounds good to me though, looks like the previous post by Bruce clears  
up any issues I would have and allows me to move around this in a  
config file as well.

> You could of course also apply Apple's multiple-connections-per- 
> process patch posted to this list some months ago or wait for Snow  
> Leopard which distributes Dovecot with that patch.


 From what I heard today, Snow is only going to support non PPC  
machines.  I eventually will get a Intel machine, but if I do not have  
to migrate, it would be a lot simpler on my life.  Great to know there  
is a patch, I will look into it.

Does the patch work on PPC?  Is this patch a Dovecot patch, or an OS  
patch of some form?  If you  could point me to what to search on to  
locate the details, I can start looking at it.  I would like to see if  
it would be a good idea to update the portfile for macports, in order  
to bring this to Dovecot within the MacPorts project.  That is what I  
used to install Dovecot, and it worked very well for me.

Thanks to everyone who helped me in this thread.
-- 
Scott * If you contact me off list replace talklists@ with scott@ *