[Dovecot] Login processes in Dovecot
Scott Haneda
talklists at newgeo.com
Tue Jun 9 00:40:37 EEST 2009
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@ *
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