[Dovecot] service_count=0 for imap and pop3

[Mark Moseley]

This is copy-pasted from Timo's comment in the "Todays Performance
Data for 2.0.x" thread, but I didn't want to hijack that thread. In
it, Timo says:

<snip>
service imap {
 service_count = 0
}

(i.e. reuse imap processes) reduced the system CPU usage to almost
nothing. But if you use different UIDs for different users you can't do
that.
</snip>

Is that safe to do in imap and/or pop3? Or at least no more insecure
than using service_count=0 for imap-login and pop3-login? Since I saw
that comment I've been googling around and grepping the wiki but I can
only find instances of using it with "service imap-login", not
"service imap" or "service pop3".

The mention in Timo's comment that it reduces the CPU usage by a lot
got my attention, esp for pop3. We're already using service_count=0
for pop3-login and imap-login.