mina框架出现too many open files解决办法

当mina nio产生大量socket，而且底层的socket长期处于Time_Wait状态
用netstat -p
可以查看
就会产生too many open files异常。
此时，在程序启动脚本加入
ulimit -SHn 30000
注：红色部分自定义
扩大linux文件打开数量，问题解决。
或者修改socket的等待时常。
apache的官方解决办法：
you may have a too low ulimit setup. It defaults to 1024, and each time you open a socket, that eats a file descriptor.

You have options, though :
> - either you increase this ulimit, or set it to unlimited,
> - or you lower the tcp-time-wait value so that the sockets are closed faster.