Mysql内存占用太高，8G被耗光了。

[believe_me]

有一个后台daemon程序，运行期一直保持着数据库连接。并有频繁的数据插入。
数据库有500多个表，都会被频繁的使用。
数据库运行一段时间就会发现，8G的内存竟然会被吃光了。配置文件使用的是默认的my-medium.cnf文件。
希望大虾能够提示，这个问题应该从哪些方面考虑解决。
谢谢

数据库版本信息：
Server version: 5.1.46-log Source distribution

my.cnf文件，去除了中间部分注释

# Example MySQL config file for medium systems.
#
# This is for a system with little memory (32M - 64M) where MySQL plays
# an important part, or systems up to 128M where MySQL is used together with
# other programs (such as a web server)
#
# You can copy this file to
# /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options (in this
# installation this directory is /usr/local/mysql/var) or
# ~/.my.cnf to set user-specific options.
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the "--help" option.

# The following options will be passed to all MySQL clients
[client]
#password = your_password
port = 3306
socket = /tmp/mysql.sock

# Here follows entries for some specific programs

# The MySQL server
[mysqld]
port = 3306
socket = /tmp/mysql.sock
skip-locking
key_buffer_size = 16M
max_allowed_packet = 1M
table_open_cache = 64
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 8M

# Replication Master Server (default)
# binary logging is required for replication
log-bin=mysql-bin

# binary logging format - mixed recommended
binlog_format=mixed


server-id = 1


[mysqldump]
quick
max_allowed_packet = 16M

[mysql]
no-auto-rehash
# Remove the next comment character if you are not familiar with SQL
#safe-updates

[myisamchk]
key_buffer_size = 20M
sort_buffer_size = 20M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]

[believe_me]

在运行过程中查看top信息，发现cached在不断的增大。
请教会不会是由于频繁的数据插入导致的？

[rucypli]

你是怎么确定8G内存被用完了

[believe_me]

很惭愧
刚弄清楚，系统的8G内存并不是被mysql吃掉的。
只是被系统给cached起来了。
mysql实际上占用的内存只有300多个M。

[rucypli]

msyql占用内存大概就是innodb的缓存+myisam缓存+每个连接占用内存乘以连接数

[曾经的阿飞]

你使用innodb的话应该设置innodb_buffer_pool参数，否则的话将key_buffer_size设置到内存的%80左右

[ACMAIN_CHM]

先检查一下你的SESSION数，是不是有太多并发连接了？

[believe_me]

mysql> show processlist;
+------+----------+---------------------+--------------------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+------+----------+---------------------+--------------------+---------+------+-------+------------------+
| 803 | monitor | 122.11.48.133:34882 | dn_monitor | Sleep | 223 | | NULL |
| 1113 | monitor | 122.11.48.138:45172 | dn_monitor | Sleep | 4 | | NULL |
| 1114 | monitor | 122.11.48.138:45173 | dn_monitor | Sleep | 4 | | NULL |
| 1115 | iamadmin | 127.0.0.1:35192 | dn_monitor | Sleep | 19 | | NULL |
| 1116 | iamadmin | 127.0.0.1:35193 | dn_monitor | Sleep | 19 | | NULL |
| 1117 | iamadmin | 127.0.0.1:35194 | dn_monitor | Sleep | 19 | | NULL |
| 1118 | iamadmin | 127.0.0.1:35195 | dn_monitor | Sleep | 19 | | NULL |
| 1119 | iamadmin | 127.0.0.1:35196 | dn_monitor | Sleep | 19 | | NULL |
| 1120 | monitor | 58.221.148.162:1899 | information_schema | Sleep | 1355 | | NULL |
| 1451 | root | localhost | NULL | Query | 0 | NULL | show processlist |
+------+----------+---------------------+--------------------+---------+------+-------+------------------+
10 rows in set (0.00 sec)

session看上去没太大的异常啊

[believe_me]

补充一下系统信息啊：
Linux 2.6.9-42.ELsmp
64位
CPU： Intel(R) Xeon(R) CPU E5405 @ 2.00GHz

[yuwenbao]

用lsof 跟一下你的mysql

[believe_me]

# lsof | grep mysql | wc -l
254
同时
table_open_cache 值为 256
应该不存在打开文件过多的问题。