if one issues ulimit -n on a system without open file limits OR does the equivalent in /etc/system the orbd deadlogs and
consumes 1 cpu

$ ulimit -n 256
$ orbd -ORBDebug orbd -ORBInitialPort 2010 -ORBInitialHost sunccsparc
ORBD begins initialization.
ORBD is ready.
ORBD serverid: 1000
activation dbdir: /home/ms104109/./orb.db
activation port: 1049
activation Server Polling Time: 1000 milli-seconds
activation Server Startup Delay: 1000 milli-seconds

the orbd consumes one CPU in the ioctl:

789/15: ioctl(11, DP_POLL, 0xB3D7F9AC) Err#22 EINVAL
789/15: ioctl(11, DP_POLL, 0xB3D7F9AC) Err#22 EINVAL
789/15: ioctl(11, DP_POLL, 0xB3D7F9AC) Err#22 EINVAL
789/15: ioctl(11, DP_POLL, 0xB3D7F9AC) Err#22 EINVAL

in our case it's 25%, since it's a 4 CPU V440:

$ ps -efl|egrep 'orbd|PID'
 F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD
 0 O ms104109 789 671 25 99 20 ? 44561 08:28:56 pts/1 8:59 orbd -ORBDebug orbd -ORBInitialPort

java is:

java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Server VM (build 1.5.0_06-b05, mixed mode)

System is:

                         Solaris 10 3/05 s10_74L2a SPARC
           Copyright 2005 Sun Microsystems, Inc. All Rights Reserved.
                        Use is subject to license terms.
                            Assembled 22 January 2005

please have a look at the attached pstack output.

you can reproduce this case on any Solaris/SPARC box.