[Dovecot] Problems with the pop3 part of dovecot

[Brandon Lamb]

On Sun, Oct 26, 2008 at 10:15 AM, Timo Sirainen <tss at iki.fi> wrote:
> On Sun, 2008-10-26 at 09:57 -0700, Brandon Lamb wrote:
>> basically I need to find out where to start looking to find out what
>> is the problem with my dovecot pop3 setup. I switched from courier
>> imap/pop3 to dovecot imap/pop3. I have had super high loads (40+ and
>> overnight one server went to 511) and its been a nightmare fighting
>> with this new setup for the last two weeks.
>>
>> I did manage to narrow the problem down to it being with the pop3 part
>> of dovecot. I am not sure why the load keeps going so high.
>
> Usually this is because Dovecot wants to calculate the messages' virtual
> sizes. See maildir performance in http://wiki.dovecot.org/POP3Server.
> There were also some issues with this where Dovecot didn't always add
> the virtual size to dovecot-uidlist, but they were fixed in v1.1.5.
>
> So the initial high loads are expected if your file names don't
> contain ,W=size in them, but after that it should slow down. Of course
> if your new messages don't contain ,W= in them either, the load is still
> higher than it could be (but then again, Courier does the same thing so
> it shouldn't be higher than with Courier).
>
> One possibility would be to just make Dovecot violate POP3 spec and
> return file sizes as message sizes. Some servers like qmail-pop3d do
> that and they apparently work well enough.. This could be done by
> changing mail_get_virtual_size to mail_get_physical_size in
> src/pop3/client.c

Im willing to try this, I really dont want to go back to courier,
dovecot just seems like a way cleaner setup. I found the line to edit
so I will recompile and give that a try.

I did modify exim to add the W=size but it also required use_crlf and
that seemed to break something else. I also found a couple posts
saying to use INDEX=MEMORY for the pop3 part, but I didnt understand
if that actually DISABLED pop3 using indexes or if it really stored
something in memory, and if so what happens on a reboot, so I am
confused on if i should tell the pop3 part to use the same
/dovecot-index that I specified for imap.

I also dont know if I made so many changes that I didnt give any of
them time to work themselves out. We were just in panic mode trying to
put out fires hehe.