imap service count>1 (was System load spike ...)

[Joseph Tam]

> I'm running dovecot with quite a lot of users and lots of active imap
> connections (like 20'000). I'm using different user IDs for users, so I
> need to have imap {service_count=1} - i.e. I have a lots of imap
> processes running.

I had a misconception this service's service_count was non-adjustable.

 	(https://wiki.dovecot.org/Services on imap service)

 	service_count can be changed from 1 if only a single UID is used
 	for mail users. This is improves performance, but it's less
 	secure, because bugs in code may leak email data from another
 	user's earlier connection.

How easy would it be to implement a hybrid solution that maps all
imap service for a unique UID to a single worker process.  It would
result in modest performance gain for busy servers, and data leakage
security would be minimal.

Joseph Tam <jtam.home at gmail.com>