[Dovecot] Dovecot performance under high load (vs. Courier)

[Timo Sirainen]

On 22.6.2012, at 0.58, Michael M Slusarz wrote:

>> I think the conclusion is that imapproxy is not necessary.  There are some advantages (eg with high network latency between web and imap server, and reducing apparent login count), and some disadvantages (extra complexity, slowdown)
> 
> Not entirely true.  See this thread:
> 
> http://markmail.org/thread/z7ctwle2go6zafas
> 
> Thread in short: imapproxy provides benefits for more MUAs that take advantage of the XIMAPPROXY feature (only IMP, AFAIK), and Timo is/was considering adding a similar state saving feature to Dovecot 2.2.

Well, I had completely forgotten about it :) Reading my old mail:

> There isn't a whole lot of state to be saved really. Mailbox GUID, UIDVALIDITY,
> HIGHESTMODSEQ gives the mailbox state. Then you have the language/etc. states.
> Clients could restore their earlier state from days ago, as long as Dovecot
> still has the necessary .log records available (similar to how QRESYNC works).

Yeah .. Perhaps something like:

1. if client issues LOGOUT XSTATE

2. And server sees that it can actually save all of the state (some things are a bit tricky, and probably not worth the trouble in initial implementation)

3. Then the server server sends
* OK XSTATE <string>
* BYE 

4. The client can pipeline after LOGIN/AUTHENTICATE:
a XSTATERESTORE <string>
a OK Yeah!
or
a NO Not gonna work.

Perhaps even a real RFC for this thing? .. If it's worth it.. Would save at least a few X bytes from network traffic :)