100% of CPU utilization postgres process

Hello,

I observed the event that CPU utilization of the process related to postgres
records almost 100% for unknown reason. It would be appreciated if any of you
provide any information on this.

The following line is a part of the result of "ps -auxeww".
=============================================================
pgsql 682 99.0 0.1 9336 2740 ?? Rs 27Nov08 343573:19.27 USER=pgsql MAIL=/var/mail/pgsql HOME=/usr/local/pgsql BLOCKSIZE=K PGLOCALEDIR=/usr/local/share/locale PGSYSCONFDIR=/usr/local/etc/postgresql PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/sbin:/usr/local/bin:/usr/local/pgsql/bin SHELL=/bin/sh PWD=/usr/local/pgsql FTP_PASSIVE_MODE=YES PGDATA=/sa/db postgres: stats collector process (postgres)
=============================================================

Judging from the result, I could see that stats collector process caused this unusually high CPU utilization rate.
I found similar problem at http://archives.postgresql.org/pgsql-general/2008-06/msg00934.php, although there seemed
no clear cause proven nor the statement that it's because of postgres bug.

Also, the following message was seen in the postgres log.
==========================================================================================
Nov 12 02:49:53 postgres[681]: [2-1] WARNING: worker took too long to start; cancelled
Nov 12 02:50:53 postgres[681]: [3-1] WARNING: worker took too long to start; cancelled
…
Nov 12 11:14:12 postgres[681]: [506-1] WARNING: worker took too long to start; cancelled
Nov 12 11:15:12 postgres[681]: [507-1] WARNING: worker took too long to start; cancelled
==========================================================================================
Once the message which started with "postgres[xxx]" appeared, it had been repeated until
the OS was manually shut down. I'm not sure if each of the two could happen separately nor
if one of the two could trigger the other.

Do any of you happen to know more than what was posted at
http://archives.postgresql.org/pgsql-general/2008-06/msg00934.php ?

The event above was observed under the condition as follows.

-Postgres version : "PostgreSQL 8.3.3 on i386-portbld-freebsd7.0, compiled by GCC cc (GCC) 4.2.1 20070719 [FreeBSD]"
(It was installed via ports.)

-To connect the PostgreSQL Database, the following drivers are used.
php5-pdo_pgsql-5.2.12
p5-DBD-Pg-2.16.0

-Operating system and version
・FreeBSD 7.0-RELEASE-p2

-Hardware
・CPU : Intel, Xeon2.4
・RAM : 2GB RAM
・Storage

　　RAID controller : LSI MegaRAID

　　　-battery backed cache : none

　　　-write-back : disabled

　　　-Software RAID : not used

　　　-SAN : not used

　　　-disk configuration :

　　　　3 HITACHI 7,200rpm SATA disks in RAID5

　　　- filesystem : ufs

Regards,

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