imapd's hang when maxchild count is reached

Hi,

we are currently testing our installation of cyrus-imapd 2.1.11 using a 
self-written Perl script that's imitating real use. We intend to contribute 
the script when we've cleaned it up a little. Anyway, during our tests we 
noticed something strange. In /etc/cyrus.conf we have the line:

 imap          cmd="imapd" listen="cyrus.rrz.uni-koeln.de:imap" prefork=10 
maxchild=200

When the number of impad processes reaches 200, no more processes are 
spawned, just as it should be. However, sometimes, not immediately, but 
definitely after a while *all* imapd processes will hang if we try to open 
more connections to port 143. This is 100% reproducible. If we kill one of 
the scripts and the number of processes goes down, all the imapd's get 
unstuck, but not until that happens.

I've checked the archives but haven't seen mention of this problem. Is this 
a known issue? Is there a workaround?

This is on Red Hat Advanced Server 2.1:
cyrus.rrz.uni-koeln.de> ver
name       : Cyrus IMAPD
version    : v2.1.11-Invoca-RPM-2.1.11-16 2002/12/04 14:53:12
vendor     : Project Cyrus
support-url: http://asg.web.cmu.edu/cyrus
os         : Linux
os-version : 2.4.9-e.10enterprise
environment: Cyrus SASL 2.1.10
            Sleepycat Software: Berkeley DB 4.0.14: (November 18, 2001)
            OpenSSL 0.9.6b [engine] 9 Jul 2001
            CMU Sieve 2.2
            TCP Wrappers
            mmap = shared
            lock = fcntl
            nonblock = fcntl
            auth = unix
            idle = poll
            dirhash = full
            mboxlist.db = skiplist
            subs.db = flat
            seen.db = skiplist
            duplicate.db = db3-nosync
            tls.db = db3-nosync

--
Sebastian Hagedorn M.A. - RZKR-R1 (Flachbau), Zi. 18, Robert-Koch-Str. 10
Zentrum für angewandte Informatik - Universitätsweiter Service RRZK
Universität zu Köln / Cologne University - Tel. +49-221-478-5587

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