连接数据库切忌要使用完毕断开连接

查看max_connections
进入MySQL，用命令：show variables
查看数据库最大可连接数的变量值：max_connections

查看threads_connected
进入MySQL，用命令：show status
查看当前活动的连接线程变量值：threads_connected

设置max_connections
设置办法是在my.cnf文件中，添加下面的最后红色的一行：
[mysqld]
port=3306
#socket=MySQL
skip-locking
set-variable = key_buffer=16K
set-variable = max_allowed_packet=1M
set-variable = thread_stack=64K
set-variable = table_cache=4
set-variable = sort_buffer=64K
set-variable = net_buffer_length=2K
set-variable = max_connections=32000