ports/164533: net/isc-dhcp41-server and net/isc-dhcp42-server eat CPU

[Eugene M. Zheganin]

>Number:         164533
>Category:       ports
>Synopsis:       net/isc-dhcp41-server and net/isc-dhcp42-server eat CPU
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-ports-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jan 27 06:10:11 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Eugene M. Zheganin
>Release:        9.0-RELEASE
>Organization:
RealService LLC
>Environment:
FreeBSD taiga 9.0-RELEASE FreeBSD 9.0-RELEASE #1: Mon Jan 23 13:36:16 YEKT 2012     emz at taiga:/usr/obj/usr/src/sys/TAIGA  amd64
>Description:
net/isc-dhcp41-server and net/isc-dhcp42-server eat enormous amount of CPU.
I tried both versions.
Everything was fine on 8.2.
Everything is still fine on the failover sibling still running 8.2 with the same config (the only difference is that it's a master).

Top:

last pid: 44964;  load averages:  2.97,  2.43,  2.40                                            up 3+19:54:21  11:56:18
247 processes: 3 running, 244 sleeping
CPU:  4.0% user,  0.0% nice, 23.7% system, 23.0% interrupt, 49.2% idle
Mem: 292M Active, 55M Inact, 3396M Wired, 65M Cache, 418M Buf, 83M Free
Swap: 8192M Total, 1696M Used, 6496M Free, 20% Inuse

  PID USERNAME    THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
44604 dhcpd         1  92    0 24664K  4928K CPU2    2   2:29 69.87% dhcpd
44938 dhcpd         1   4    0 20696K  7544K RUN     1   0:11 30.96% dhcpd

(these are -6 and -4 daemons, running only one of them doesn't help either).

Also what is weird: sibling under 8.2 eats 3% after starting daemon, then this number is decreasing to 0%; 9.0 eats 20% after starting, then this number increases to 70%.
>How-To-Repeat:
Get a FreeBSD 9.0, install any of net/isc-dhcp4*-server ports, run it.
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: