mysqld out of memory

[Valentin Bud]

Hello community,

 Today I had for the first time this problem with mysql on a production
server.
The following start flowing in the mysql-err.log
090210  9:12:17 [ERROR] /usr/local/libexec/mysqld: Out of memory (Needed
1676280 bytes)

Doing a top resulted in mysql eating up about 2GB of memory of a total of 4
GB which
i have on that particular box. After googling a little i found some post on
the mailing list about
setting kern.maxdsiz to 1GB. After that I have checked out the kern.maxdsiz
with
# limits -Hd
Resource limits (current):
  datasize          1048576 kB

I noticed that it is already at 1GB. Now my problem is how can i avoid this
in the future because
on that production server mysql is crucial or in case it happens how ca I be
the first to know
of that problem?

I will post some info about the server
# uname -a
FreeBSD nemty 7.0-RELEASE FreeBSD 7.0-RELEASE #5: Tue Mar 25 16:38:28 CET
2008     root at nemty:/usr/obj/usr/src/sys/NEMTY  i386

# mysqladmin version
...
Server version          5.0.75-log
...
If there are any other info that might help in troubleshooting this problem
i will be glad
to provide them. Thanks for yout input.

a great day,
v