[Dovecot] quick, quick, slow...

[Jeroen Scheerder]

Hi,

I'm (still) evaluating dovecot for a switch from UW in the near
future.  All the following happens on a Solaris server.

Functionally, all is well.  However, I see strange phenomena.

Normally, dovecot is pretty swift.  Every now and then, though,
things slow down to a crawl.  Everything seems to be working,
still, but a few orders of magnitude slower.  A copy of an
outgoing message (of a few lines) to my Out box, which 
normally succeeds nearly instantly, suddenly takes over
30 minutes, for example.

Obvious things to look for would be conflicting locking strategies.
As far as I know, though, my mail delivery agent (procmail) and
all mail handling software use dotlocking, fcntl lockf, in that
order), as does dovecot.

In syslog there's nothing to see, except an occasional

	SSL_accept() syscall failed: EOF

messsage, which I can correlate to my service monitoring
software (nagios), which checks for the presence of the imaps
service.

When this happens and I quit my mail agent (Thunderbird), an imap
process seems to remain on the server.  Killing that does not resolve
the extreme slowdown; that persists on consecitive reruns of my
mailer.

I'm at a loss here.  Any hints?