MYSQL四个timeout参数的含义

4个timeout都是为了防止某一个链接长时间占用一数据库的描述符,又不干事情,或者网络有问题没有释放这个描述符,线程阻塞种种资源浪费的情况.我们要主动的"卡"掉对端!

首先看看这4个timeout在mysql5.1手册里的英文解释:

connect_timeout
The number of seconds that the mysqld server waits for a connect packet before responding with Bad handshake.
interactive_timeout
The number of seconds the server waits for activity on an interactive connection before closing it.
wait_timeout
The number of seconds the server waits for activity on a noninteractive connection before closing it.
net_read_timeout
The number of seconds to wait for more data from a connection before aborting the read.
net_write_timeout
The number of seconds to wait for a block to be written to a connection before aborting the write.

从意思上可以理解为

connect_timeout在获取连接阶段（authenticate）起作用，

interactive_timeout和wait_timeout在连接空闲阶段（sleep）起作用，

net_read_timeout和net_write_timeout在连接繁忙阶段（query）起作用。