How many copies of the mupdate master should run?

[Gary Mills]

On our mupdate master server, mupdate is defined in cyrus.conf with
`prefork=1'.  However, two of them are running, both children of
master...

       UID   PID  PPID   C    STIME TTY         TIME CMD
     cyrus  1594   483   0   Apr 15 ?           0:00 mupdate -C /etc/mupdate/imapd.conf -m
     cyrus  1596   483   0   Apr 15 ?          22:18 mupdate -C /etc/mupdate/imapd.conf -m

The second one seems to be doing all the work.  What's the first one for?
Both have opens on the unix-domain socket.  Only the second one has TCP
connections.

In fact, there were three started, but one terminated...

  Apr 15 22:09:16 castor mupdate[1595]: [ID 166678 local6.error] bind: /imap/mupdate/conf/socket/mupdate.target: Address already in use
  Apr 15 22:09:16 castor mupdate[1595]: [ID 702911 local6.error] bind failed
  Apr 15 22:09:16 castor master[483]: [ID 684980 local6.warning] service mupdate pid 1595 in READY state: terminated abnormally

What's going on here?

-- 
-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-