Skiplist problems, locking problems with seen files

[Leena Heino]

Some of our users have reported that they have been locked out of their 
accounts.

When I examined one such occurence it seemed that one of the imapd 
processes had acquired a write lock to user's seen file and doing 
absolutely nothing to that seen file just holding the writelock. When this 
process was killed user was able to access his mail again.

Now this problem seems to be spreading. Imapd processes just hanging on to 
their writelocks to seen files doing nothing.

What could cause such a problem?

Current version is:
version    : v2.3.12p2 2008/04/24 16:09:27
os         : SunOS
os-version : 5.10
environment: Built w/Cyrus SASL 2.1.22
              Built w/Sleepycat Software: Berkeley DB 4.4.20: (January 10, 2006)
              lock = fcntl
              nonblock = fcntl

-- 
   Leena Heino              University of Tampere / Computer Centre
   ( liinu at uta.fi )      ( http://www.uta.fi/laitokset/tkk )