防火墙拦截导致Redis连接异常，JedisConnectionException: Could not get a resource from the pool

问题结论&解决方案

防火墙拦截导致，找到服务的端口，然后在防火墙中配置给端口放行，同时设置重启后也生效

在root权限下执行：

iptables -A INPUT -p tcp --dport 80 -j ACCEPT

然后执行(即时生效，重启失效)：

service iptables stop
service iptables start

要想重启后也生效，则执行：

chkconfig iptabels on
chkconfig iptabels off

问题场景

给客户线上排查问题OA服务的应用获取登录框加载异常缓慢，客户有部署Redis，通过分析线程日志发现并结合业务日志锁定到如下报错内容，JedisConnectionException: Could not get a resource from the pool

redis.clients.jedis.exceptions.JedisConnectionException: Could not get a resource from the pool
	at redis.clients.util.Pool.getResource(Pool.java:53)
	at redis.clients.jedis.JedisPool.getResource(JedisPool.java:226)
	
Caused by: redis.clients.jedis.exceptions.JedisConnectionException: java.net.NoRouteToHostException: 没有到主机的路由 (Host unreachable)
	at redis.clients.jedis.Connection.connect(Connection.java:207)
	at redis.clients.jedis.BinaryClient.connect(BinaryClient.java:93)
	at redis.clients.jedis.BinaryJedis.connect(BinaryJedis.java:1767)
	at redis.clients.jedis.JedisFactory.makeObject(JedisFactory.java:106)
	at org.apache.commons.pool2.impl.GenericObjectPool.create(GenericObjectPool.java:868)
	at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:435)
	at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:363)
	at redis.clients.util.Pool.getResource(Pool.java:49)

问题分析

根据日志直接判断应该是redis服务不可用，那么要么是服务本身有问题，比如没启动，要么就是服务不可达。然后借助网上的经验判断有了思路，可能是防火墙拦截的原因，客户最近有重启过服务，可能防火墙配置好了,重启又还原了导致

防火墙检测的相关命令

1、查看已经开放的端口

firewall-cmd --list-ports

2、放行端口

firewall-cmd --zone=public --add-port=8080/tcp --permanent

--zone 作用域

--permanent 永久生效

3、重启防火墙

systemctl reload firewalld

4、查询指定端口是否开启成功

firewall-cmd --query-port=5601/tcp

5、停止防火墙

systemctl stop firewalld

或：

systemctl stop firewalld.service

6、启动防火墙

systemctl start firewalld

或：

systemctl start firewalld.service

7、查看防火墙是否在运行

systemctl status firewalld