Spring Boot启动时数据库连接ConcurrentModificationException异常问题

将Spring版本从1.5.6升级至2.7.9，同时替换数据库驱动为org.mariadb.jdbc.Driver（对应MariaDB 10.5.16）后，应用启动抛出如下异常：

java.util.ConcurrentModificationException: null
    at java.util.Hashtable$Enumerator.next(Hashtable.java:1387)
    at org.mariadb.jdbc.Configuration.mapPropertiesToOption(Configuration.java:611)
    at org.mariadb.jdbc.Configuration.parseInternal(Configuration.java:589)
    at org.mariadb.jdbc.Configuration.parse(Configuration.java:518)
    at org.mariadb.jdbc.Driver.connect(Driver.java:96)
    at org.mariadb.jdbc.Driver.connect(Driver.java:27)
    at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138)
    at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:364)
    at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206)
    at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:476)
    at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:561)
    at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115)
    at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112)
    at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcEnvironmentInitiator.java:181)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:68)
    at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:272)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:246)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:223)
    at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:175)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:295)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:252)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:223)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:173)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:127)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1460)
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1494)
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:396)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1863)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1800)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:620)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1154)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:908)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:731)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:307)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1303)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1292)
    at com.iba.asokp.analitycs.Application.main(Application.java:15)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:108)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:58)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:65)

当前application.properties配置：

# connection
spring.notification.driver-class-name=org.mariadb.jdbc.Driver
spring.notification.jdbc-url=jdbc:mariadb://${DB_CONNECTION_URL}:${DB_CONNECTION_PORT}/ibacontrol?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull
spring.notification.username=${DB_CONNECTION_USERNAME}
spring.notification.password=${DB_CONNECTION_PASSWORD}
spring.notification.name=ibacontrol
spring.notification.maxActive=5
spring.notification.test-while-idle=true
spring.notification.validation-query=SELECT 1
spring.notification.time-between-eviction-runs-millis=100000
spring.notification.min-evictable-idle-time-millis=10000
spring.data.jpa.repositories.enabled=false
isnotify.enable=true
url=jdbc:mariadb://${DB_CONNECTION_URL}:${DB_CONNECTION_PORT}/ibacontrol
notificator.threadPool=100
reactor.threadPool=100
enabled=true
server=server
from=from
login=login
pass=pass

解决方案 #

• 升级MariaDB驱动版本：Spring Boot 2.7.x与MariaDB驱动2.7.x及以上版本兼容性更好，建议将mariadb-java-client升级到2.7.x系列（如2.7.8），避免旧版本驱动内部遍历配置时的并发修改问题。
• 修正数据源配置参数：Spring Boot 2.x默认使用HikariCP，旧的maxActive参数需替换为HikariCP标准参数maximum-pool-size；同时检查自定义数据源前缀spring.notification.*是否正确绑定到DataSource Bean，确保配置被正确识别。
• 修复JDBC URL转义问题：配置中的&是双重HTML转义，在application.properties中应直接使用&分隔参数，修改后的URL应为：jdbc:mariadb://${DB_CONNECTION_URL}:${DB_CONNECTION_PORT}/ibacontrol?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull。
• 删除冗余配置：移除独立的url=jdbc:mariadb://...属性，该配置可能被驱动或Spring意外读取，导致配置冲突引发遍历异常。
• 开启驱动调试日志：若以上步骤无效，添加JVM启动参数-Dorg.mariadb.jdbc.debug=true，查看驱动处理配置的详细日志，定位是否存在内部并发修改或系统属性被意外修改的情况。

内容的提问来源于stack exchange，提问作者NikiTer