linux TCP: time wait bucket table overflow

早上一台rabbitmq和Java所在的服务器，客户端反馈超级卡，看io和cpu都不高。发现六七万消息挤压，临时性问题解决之后，看/var/log/messages，发现很多TCP: time wait bucket table overflow，如下所示：

Nov 22 10:36:08 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:36:08 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: __ratelimit: 47 callbacks suppressed
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow
Nov 22 10:37:07 iZ237hn51s7Z kernel: TCP: time wait bucket table overflow

经查，发现net.ipv4.tcp_max_tw_buckets = 5000 ##已经修改

netstat -ano | grep wait | wc -l发现4400多，进一步查询，发现大量本机到mysql的连接状态处于该状态，进一步发现，有个应用的maxStatement被设置成了0。