Strange locking problems

[Michael Plate]

Hi,

I am using postfix / cyrus on a Gentoo Linux box for ahem...a while (10 
years) now.

Current cyrus is 2.4.17, postfix 2.9.5 , the box is a dual Xeon (2.4 
GHz, family 15, model2, stepping 7), 2 GB memory, a HW RAID 5 (ICP 
Vortex, now Intel), and yes it 10 years old this year. Never had 
problems and Gentoo grew up and so did cyrus.
We use lmtp (127.0.0.1:24) for local delivery.

Starting from around December 2012 I have sometimes unreachable INBOX.
This might happen after some OS update, but I can't remember something 
special.
People can login, but no folder (INBOX) can be selected.

The reason seems to be hanging connections between postfix and cyrus:

Mar 25 15:29:44 bib-ws13 postfix/lmtp[21841]: F0FCA6EE9A7: 
to=<some_user at our.domain.local>, relay=127.0.0.1[127.0.0.1]:24, 
delay=19018, delays=18718/0.02/0/300, dsn=4.4.2, status=deferred 
(conversation with 127.0.0.1[127.0.0.1] timed out while sending MAIL FROM)
[multiple times]

Restarting cyrus solved the problem. There is a couple of lmtpd / imapd 
on the users lockfile when using lsof with grep by username.

I'm - hopefully - not using any BDB stuff anymore:

imapd.conf:

duplicate_db: skiplist
mboxlist_db: skiplist
quota_db: quotalegacy
tlscache_db:skiplist
annotation_db:          skiplist
seenstate_db:           flat

The whole Linux is current, so I am a little bit lost.

CU

Michael