问题遇到的现象和发生背景
应用后台日志发现错误：
2022-05-01 06:12:23.422 [demo-app: N/A] [ERROR] com.zaxxer.hikari.pool.HikariPool - HikariPool-lic-c-1 - Error thrown while acquiring connection from data source
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
The last packet successfully received from the server was 5,004 milliseconds ago. The last packet sent successfully to the server was 5,004 milliseconds ago.
问题相关代码，请勿粘贴截图
没有代码，
数据库连接池配置是：
type: com.zaxxer.hikari.HikariDataSource
driver-class-name: com.mysql.cj.jdbc.Driver
jdbc-url: jdbc:mysql://192.123.0.71:3306/lk?characterEncoding=UTF-8&useSSL=false&serverTimezone=UTC&allowMultiQueries=true
username: root
password: root
pool-name: HikariPool-lk
#连接最大存活时间,默认值30分钟.设置应该比mysql设置的超时时间短
max-lifetime: 30000
#最大连接数，小于等于0会被重置为默认值10；大于零小于1会被重置为minimum-idle的值
maximum-pool-size: 30
#连接超时时间:毫秒，小于250毫秒，否则被重置为默认值30秒
connection-timeout: 30000
#最小空闲连接，默认值10，小于0或大于maximum-pool-size，都会重置为maximum-pool-size
minimum-idle: 10
# 默认是600000毫秒，即10分钟。如果idleTimeout+1秒>maxLifetime 且 maxLifetime>0，则会被重置为0；
# 如果idleTimeout!=0且小于10秒，则会被重置为10秒。如果idleTimeout=0则表示空闲的连接在连接池中永远不被移除
# 只有当minimumIdle小于maximumPoolSize时，这个参数才生效，当空闲连接数超过minimumIdle，而且空闲时间超过idleTimeout，则会被移除。
idle-timeout: 28000
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP</artifactId>
<version>3.4.5</version>
</dependency>
运行结果及报错内容
2022-05-01 06:12:23.422 [demo-app: N/A] [ERROR] com.zaxxer.hikari.pool.HikariPool - HikariPool-lic-c-1 - Error thrown while acquiring connection from data source
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
The last packet successfully received from the server was 5,004 milliseconds ago. The last packet sent successfully to the server was 5,004 milliseconds ago.
at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:172)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
at com.mysql.cj.jdbc.ConnectionImpl.isReadOnly(ConnectionImpl.java:1557)
at com.mysql.cj.jdbc.ConnectionImpl.isReadOnly(ConnectionImpl.java:1527)
at com.zaxxer.hikari.pool.PoolBase.setupConnection(PoolBase.java:402)
at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:363)
at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206)
at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:477)
at com.zaxxer.hikari.pool.HikariPool.access$100(HikariPool.java:71)
at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:725)
at com.zaxxer.hikari.pool.HikariPool$PoolEntryCreator.call(HikariPool.java:711)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: com.mysql.cj.core.exceptions.CJCommunicationsException: Communications link failure
The last packet successfully received from the server was 5,004 milliseconds ago. The last packet sent successfully to the server was 5,004 milliseconds ago.
at sun.reflect.GeneratedConstructorAccessor130.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:60)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:99)
at com.mysql.cj.core.exceptions.ExceptionFactory.createException(ExceptionFactory.java:139)
at com.mysql.cj.core.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:155)
at com.mysql.cj.mysqla.io.MysqlaProtocol.readPacket(MysqlaProtocol.java:546)
at com.mysql.cj.mysqla.io.MysqlaProtocol.checkErrorPacket(MysqlaProtocol.java:712)
at com.mysql.cj.mysqla.io.MysqlaProtocol.sendCommand(MysqlaProtocol.java:651)
at com.mysql.cj.mysqla.MysqlaSession.sendCommand(MysqlaSession.java:518)
at com.mysql.cj.mysqla.MysqlaSession.queryServerVariable(MysqlaSession.java:1318)
at com.mysql.cj.jdbc.ConnectionImpl.isReadOnly(ConnectionImpl.java:1545)
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:170)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at com.mysql.cj.core.io.ReadAheadInputStream.fill(ReadAheadInputStream.java:107)
at com.mysql.cj.core.io.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:150)
at com.mysql.cj.core.io.ReadAheadInputStream.read(ReadAheadInputStream.java:180)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at com.mysql.cj.core.io.FullReadInputStream.readFully(FullReadInputStream.java:64)
at com.mysql.cj.mysqla.io.SimplePacketReader.readHeader(SimplePacketReader.java:66)
at com.mysql.cj.mysqla.io.TimeTrackingPacketReader.readHeader(TimeTrackingPacketReader.java:54)
at com.mysql.cj.mysqla.io.MultiPacketReader.readHeader(MultiPacketReader.java:57)
at com.mysql.cj.mysqla.io.MysqlaProtocol.readPacket(MysqlaProtocol.java:540)
我的解答思路和尝试过的方法
检查配置， 调整数据库端的 timeout 配置； 还是一样的结果。
不懂，为什么出现有 5,004 milliseconds 的错误， 因为我并没有设置 5s;
我实际设置的是30s， 如果是5s 就读超时，那么如何解释？
我想要达到的结果
不出现 这个错误：
