记druid 在配置中心下的一个大坑
Posted flyaway2013
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了记druid 在配置中心下的一个大坑相关的知识，希望对你有一定的参考价值。
把我们的dubbo 应用移步到配置中心上去之后，发现我们的应用过一段时间就会出现cpu 100%的情况 （大概是12个小时），一开始cpu占用是2-5% 的样子，什么都没做，后面竟然用尽了cpu。。
把jvm 线程堆栈打印一下，发现线程数竟然达到了上万..... 发现最多是这样的一个线程：
"com.alibaba.nacos.client.Worker.fixed-192.168.11.196_8848-1f3c60b6-3e28-44eb-9798-7f7eeeff6a8d" #138 daemon prio=5 os_prio=0 tid=0x0000000026c49000 nid=0xf60 waiting on condition [0x000000002aebe000]
java.lang.Thread.State: TIMED_WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x000000079c3a15a8> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
我们的配置中心是nacos，从com.alibaba.nacos.client.Worker.fixed来看， 跟nacos 好像有点关系。事实也是如此，我们之前的没有用nacos ， 是根本没有这个问题的。 但是，也不是每个应用都是这样， 我们的网关应用就没这个问题。。
spring-cloud-alibaba-dependencies 刚刚从0.2.1.RELEASE 升级到了 0.2.2.RELEASE， 难道这个有关系？ 和 spring-cloud-dependencies 的兼容性问题？和 spring-cloud-starter的兼容性问题？
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Finchley.SR1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-alibaba-dependencies</artifactId>
<version>0.2.2.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter</artifactId>
<version>2.0.2.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
但退回原来的版本，问题依旧。
重新写了一个spring boot 程序，没有问题。 把原来的那一套加上，问题出现了。 观察发现数据源似乎有问题。
怀疑是nacos 的坑。com.alibaba.nacos.client.Worker 是什么鬼？ 全局搜索类名， 没发现，难道不是一个类吗？ fixed 是一个方法吗？ 找不到。 如是把nacos 1.0.0 的源码下载了下来。 全局搜索类com.alibaba.nacos.client.Worker， 还是没发现。全局全文搜索fixed ,发现了com/alibaba/nacos/client/config/impl/ServerListManager.java。通过本机调试，发现了 com.alibaba.nacos.client.config.impl.ClientWorker， 同时发现了com.alibaba.nacos.client.Worker 字眼 , 原来是写死的！ 依然不清楚问题原因。
直觉告诉我 正是 ClientWorker 不断创建了我们的 “问题线程”， 但是其机制我并不太清楚。贸然的调试没有发现根本原因，反而把我弄得一头雾水。 我得看一下源码。
不断的加断点， 发现了 com.alibaba.nacos.client.config.impl.CacheData 的 safeNotifyListener 方法， 其中的 listener.receiveConfigInfo 方法似乎出现了问题， 执行到了1的地方，2却不会执行，真是奇了怪了， 难道陷入了死循环？
private void safeNotifyListener(final String dataId, final String group, final String content, final String md5, final ManagerListenerWrap listenerWrap) { final Listener listener = listenerWrap.listener; Runnable job = new Runnable() { public void run() { ClassLoader myClassLoader = Thread.currentThread().getContextClassLoader(); ClassLoader appClassLoader = listener.getClass().getClassLoader(); try { if (listener instanceof AbstractSharedListener) { AbstractSharedListener adapter = (AbstractSharedListener)listener; adapter.fillContext(dataId, group); CacheData.LOGGER.info("[{}] [notify-context] dataId={}, group={}, md5={}", new Object[]{CacheData.this.name, dataId, group, md5}); } Thread.currentThread().setContextClassLoader(appClassLoader); ConfigResponse cr = new ConfigResponse(); cr.setDataId(dataId); cr.setGroup(group); cr.setContent(content); CacheData.this.configFilterChainManager.doFilter((IConfigRequest)null, cr); String contentTmp = cr.getContent(); listener.receiveConfigInfo(contentTmp); //1 出错！ listenerWrap.lastCallMd5 = md5; // 2 CacheData.LOGGER.info("[{}] [notify-ok] dataId={}, group={}, md5={}, listener={} ", new Object[]{CacheData.this.name, dataId, group, md5, listener}); } catch (NacosException var9) { CacheData.LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} errCode={} errMsg={}", new Object[]{CacheData.this.name, dataId, group, md5, listener, var9.getErrCode(), var9.getErrMsg()}); } catch (Throwable var10) { //3 异常到了这里来， 但是这个异常并没有打印出来！！
CacheData.LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} tx={}", new Object[]{CacheData.this.name, dataId, group, md5, listener, var10.getCause()}); } finally { // 4 Thread.currentThread().setContextClassLoader(myClassLoader); } } }; long startNotify = System.currentTimeMillis(); try { if (null != listener.getExecutor()) { listener.getExecutor().execute(job); } else { job.run(); } } catch (Throwable var12) { LOGGER.error("[{}] [notify-error] dataId={}, group={}, md5={}, listener={} throwable={}", new Object[]{this.name, dataId, group, md5, listener, var12.getCause()}); } long finishNotify = System.currentTimeMillis(); LOGGER.info("[{}] [notify-listener] time cost={}ms in ClientWorker, dataId={}, group={}, md5={}, listener={} ", new Object[]{this.name, finishNotify - startNotify, dataId, group, md5, listener}); }
结果发现并不是的，原因在于 我没有在3 和 4的 地方打断点， 所以误以为是 死循环。 其实1 的地方有报错， 直接跳到了3， 所以2没有执行。 加断点给3 和 4 就发现了问题原因！listener.receiveConfigInfo 是一个接口， 其实现不确定， F7 跳入发现 实际是 com.alibaba.nacos.api.config.listener.Listener#receiveConfigInfo 方法，跟进去， 发现执行到NacosContextRefresher.this.applicationContext.publishEvent(new RefreshEvent(this, (Object)null, "Refresh Nacos config")); 的时候， 下一行似乎没有执行。。 可是publishEvent 方法怎么跟进去，这就太麻烦了。。
从3 处， 我知道了问题的cause：
Error creating bean with name ‘writeDataSource‘: Could not bind properties to ‘DruidDataSource‘ : prefix=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true t = {[email protected]14064} "org.springframework.boot.context.properties.ConfigurationPropertiesBindException: Error creating bean with name ‘writeDataSource‘: Could not bind properties to ‘DruidDataSource‘ : prefix=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true; nested exception is org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under ‘spring.datasource.write‘ to com.alibaba.druid.pool.DruidDataSource" beanType = {[email protected]7625} "class com.alibaba.druid.pool.DruidDataSource" annotation = {[email protected]14067} "@org.springframework.boot.context.properties.ConfigurationProperties(prefix=spring.datasource.write, value=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true)" beanName = "writeDataSource" resourceDescription = null relatedCauses = null detailMessage = "Error creating bean with name ‘writeDataSource‘: Could not bind properties to ‘DruidDataSource‘ : prefix=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true" cause = {[email protected]14069} "org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under ‘spring.datasource.write‘ to com.alibaba.druid.pool.DruidDataSource" target = {[email protected]14146} "[[email protected] type = com.alibaba.druid.pool.DruidDataSource, value = ‘provided‘, annotations = array<Annotation>[@org.springframework.boot.context.properties.ConfigurationProperties(prefix=spring.datasource.write, value=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true)]]" property = {[email protected]14147} "[[email protected] name = spring.datasource.write.url, value = ‘${mysql_WRITE_URL:jdbc:mysql://192.168.11.200:3418/elppmdb}?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false‘, origin = "spring.datasource.write.url" from property source "bootstrapProperties"]" name = {[email protected]14148} "spring.datasource.write" detailMessage = "Failed to bind properties under ‘spring.datasource.write‘ to com.alibaba.druid.pool.DruidDataSource" cause = {[email protected]14150} "java.lang.IllegalStateException: Unable to set value for property url" detailMessage = "Unable to set value for property url" cause = {[email protected]14164} "java.lang.reflect.InvocationTargetException" stackTrace = {StackTraceElement[59]@14166} suppressedExceptions = {[email protected]13951} size = 0 stackTrace = {StackTraceElement[40]@14152} suppressedExceptions = {[email protected]13951} size = 0 stackTrace = {StackTraceElement[35]@14072} suppressedExceptions = {[email protected]13951} size = 0 CacheData.this.name = "fixed-192.168.11.196_8848-1f3c60b6-3e28-44eb-9798-7f7eeeff6a8d"
可以看到根本原因是：Unable to set value for property url ， 难道是 nacos 上的配置中心的配置有问题？
spring: application: name: erdp_discuss_app profile: active: ${PROFILE_ACTIVE:local} cloud: nacos: discovery: server-addr: ${NACOS_SERVER_ADDR:192.168.11.196:8848} profiles: active: ${PROFILE_ACTIVE:local} jackson: time-zone: GMT+8 date-format: yyyy-MM-dd HH:mm:ss serialization: write_dates_as_timestamps: false datasource: write: url: jdbc:mysql://192.168.11.200:3418/elppmdb?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false username: elppm_user password: elppm driver-class-name: com.mysql.jdbc.Driver max-active: 20 initial-size: 1 min-idle: 3 max-wait: 60000 time-between-eviction-runs-millis: 60000 min-evictable-idle-time-millis: 300000 validation-query: SELECT ‘x‘ FROM DUAL test-while-idle: true test-on-borrow: false test-on-return: false # 配置监控统计拦截的filters，去掉后监控界面sql无法统计，‘wall‘用于防火墙 filters: stat,wall,log4j # 通过connectProperties属性来打开mergeSql功能；慢SQL记录 connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=3000 # 合并多个DruidDataSource的监控数据 #spring.datasource.useGlobalDataSourceStat=true read: url: ${MYSQL_READ_URL:jdbc:mysql://192.168.11.200:3418/elppmdb}?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false username: ${MYSQL_DB_USERNAME:elppm_user} password: ${MYSQL_DB_PASSWORD:elppm} driver-class-name: com.mysql.jdbc.Driver max-active: 20 initial-size: 1 min-idle: 3 max-wait: 60000 time-between-eviction-runs-millis: 60000 min-evictable-idle-time-millis: 300000 validation-query: SELECT ‘x‘ FROM DUAL test-while-idle: true test-on-borrow: false test-on-return: false # 配置监控统计拦截的filters，去掉后监控界面sql无法统计，‘wall‘用于防火墙 filters: stat,wall,log4j # 通过connectProperties属性来打开mergeSql功能；慢SQL记录 connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=3000 # 合并多个DruidDataSource的监控数据 #spring.datasource.useGlobalDataSourceStat=true redis: host: ${APP_REDIS_HOST:192.168.11.200} password: ${APP_REDIS_PW:Redis!123} #password: # Login password of the redis server. port: ${APP_REDIS_PORT:6479} database: 2 timeout: 1000 pool: max-active: 8 #最大连接数 max-idle: 8 #最大空闲连接数 max-wait: -1 #最大等待时间 min-idle: 0 #初始化连接数 http: multipart: enabled: true # Enable support of multi-part uploads. file-size-threshold: 4KB # Threshold after which files will be written to disk. Values can use the suffixed "MB" or "KB" to indicate a Megabyte or Kilobyte size. location: /tmp # Intermediate location of uploaded files. max-file-size: 5Mb # Max file size. Values can use the suffixed "MB" or "KB" to indicate a Megabyte or Kilobyte size. max-request-size: 50Mb # Max request size. Values can use the suffixed "MB" or "KB" to indicate a Megabyte or Kilobyte size. data: mongodb: uri: mongodb://${MONGODB_SERV_URL:192.168.11.200:27117/docs} mybatis: typeAliasesPackage: com.elead.ppm.discuss.domain configLocation: classpath:mybatis-config.xml mapperLocations: classpath:mybatis/*.xml server: port: ${SERVER_PORT:8092} erdpapp: basepath: ${RDP_BASE_PATH:/eRDPServer} logcharset: ${RDP_LOG_CHARSET:UTF-8}
可以看到，我们的配置是 数据源读写分离的， 并不是原始的那种。
我们的代码配置是：
package com.elead.platform.common.service.datasource; import com.alibaba.druid.pool.DruidDataSource; import com.baomidou.mybatisplus.entity.GlobalConfiguration; import com.baomidou.mybatisplus.enums.DBType; import com.baomidou.mybatisplus.enums.IdType; import com.baomidou.mybatisplus.plugins.PaginationInterceptor; import com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean; import com.elead.platform.common.exception.SystemException; import org.apache.ibatis.plugin.Interceptor; import org.apache.ibatis.session.SqlSessionFactory; import org.mybatis.spring.SqlSessionFactoryBean; import org.mybatis.spring.boot.autoconfigure.MybatisProperties; import org.mybatis.spring.boot.autoconfigure.SpringBootVFS; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Primary; import org.springframework.core.env.Environment; import org.springframework.core.io.DefaultResourceLoader; import org.springframework.jdbc.datasource.DataSourceTransactionManager; import org.springframework.util.ObjectUtils; import org.springframework.util.StringUtils; import javax.sql.DataSource; /** * 数据源配置 * * @author luo * */ @Configuration public class DatasourceConfig { @Autowired Environment env; /** * Write data source druid data source. * * @return the druid data source */ @Primary @Bean(name = "writeDataSource") @ConfigurationProperties("spring.datasource.write") public DruidDataSource writeDataSource() { System.out.println("+++++++++++++++++" + env.getProperty("spring.datasource.write.url")); return new DruidDataSource(); } /** * Read data source druid data source. * * @return the druid data source */ @Bean(name = "readDataSource") @ConfigurationProperties("spring.datasource.read") public DruidDataSource readDataSource() { return new DruidDataSource(); } /** * Dynamic data source data source. * * @return the data source */ @Bean(name = "dynamicDataSource") public DataSource dynamicDataSource() { DynamicDataSource dynamicDataSource = new DynamicDataSource(); dynamicDataSource.setWriteDataSource(writeDataSource()); dynamicDataSource.setReadDataSource(readDataSource()); return dynamicDataSource; } /** * Dynamic transaction manager data source transaction manager. * * @param dynamicDataSource the dynamic data source * @return the data source transaction manager */ @Bean(name = "dynamicTransactionManager") public DataSourceTransactionManager dynamicTransactionManager(@Qualifier("dynamicDataSource") DataSource dynamicDataSource) { return new DynamicDataSourceTransactionManager(dynamicDataSource); } /** * Dynamic sql session factory sql session factory. * * @param dynamicDataSource the dynamic data source * @param properties the properties * @return the sql session factory */ @Bean @ConfigurationProperties(prefix = MybatisProperties.MYBATIS_PREFIX) public SqlSessionFactory dynamicSqlSessionFactory( @Qualifier("dynamicDataSource") DataSource dynamicDataSource, MybatisProperties properties) { // final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean(); // sessionFactory.setDataSource(dynamicDataSource); // sessionFactory.setVfs(SpringBootVFS.class); // sessionFactory.setTypeAliasesPackage(properties.getTypeAliasesPackage()); // sessionFactory.setConfigLocation(new DefaultResourceLoader().getResource(properties.getConfigLocation())); // sessionFactory.setMapperLocations(properties.resolveMapperLocations()); final MybatisSqlSessionFactoryBean sessionFactory = new MybatisSqlSessionFactoryBean(); sessionFactory.setDataSource(dynamicDataSource); sessionFactory.setVfs(SpringBootVFS.class); if (StringUtils.hasLength(properties.getTypeAliasesPackage())) { sessionFactory.setTypeAliasesPackage(properties.getTypeAliasesPackage()); } if (StringUtils.hasText(properties.getConfigLocation())) { sessionFactory.setConfigLocation(new DefaultResourceLoader().getResource(properties.getConfigLocation())); } if (!ObjectUtils.isEmpty(properties.resolveMapperLocations())) { sessionFactory.setMapperLocations(properties.resolveMapperLocations()); } //翻页插件 PaginationInterceptor paginationInterceptor = new PaginationInterceptor(); paginationInterceptor.setLocalPage(true); sessionFactory.setPlugins(new Interceptor[]{ paginationInterceptor }); //全局配置 GlobalConfiguration globalConfig = new GlobalConfiguration(); globalConfig.setDbType(DBType.MYSQL.getDb()); globalConfig.setIdType(IdType.INPUT.getKey()); globalConfig.setDbColumnUnderline(true); //热加载 //globalConfig.setRefresh(true); //自动填充 globalConfig.setMetaObjectHandler(new MyMetaObjectHandler()); sessionFactory.setGlobalConfig(globalConfig); try { return sessionFactory.getObject(); } catch (Exception e) { throw new SystemException(e); } } }
根本原因都找到了，但是却不知道是哪一行报错的。 就像水中的月亮，看起来近在咫尺，却远在天边。干脆DruidDataSource 进去看看， 加几个断点吧！
做了一些代码上的注释/调整后，发现这样的错误：
detailMessage = "Error creating bean with name ‘writeDataSource‘: Could not bind properties to ‘DruidDataSource‘ : prefix=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true" cause = {[email protected]10784} "org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under ‘spring.datasource.write‘ to com.alibaba.druid.pool.DruidDataSource" target = {[email protected]10792} "[[email protected] type = com.alibaba.druid.pool.DruidDataSource, value = ‘provided‘, annotations = array<Annotation>[@org.springframework.boot.context.properties.ConfigurationProperties(prefix=spring.datasource.write, value=spring.datasource.write, ignoreInvalidFields=false, ignoreUnknownFields=true)]]" property = {[email protected]10793} "[[email protected] name = spring.datasource.write.username, value = ‘${MYSQL_DB_USERNAME:elppm_user}‘, origin = "spring.datasource.write.username" from property source "bootstrapProperties"]" name = {[email protected]10794} "spring.datasource.write" detailMessage = "Failed to bind properties under ‘spring.datasource.write‘ to com.alibaba.druid.pool.DruidDataSource" cause = {[email protected]10796} "java.lang.IllegalStateException: Unable to set value for property username" detailMessage = "Unable to set value for property username" cause = {[email protected]10810} "java.lang.reflect.InvocationTargetException" stackTrace = {StackTraceElement[60]@10812} suppressedExceptions = {[email protected]10788} size = 0 stackTrace = {StackTraceElement[41]@10798} suppressedExceptions = {[email protected]10788} size = 0
这个错误依旧没能解决问题。 但 这回我聪明了， 不断的展开cause， 我发现了 InvocationTargetException, 但是 这个发型并没有什么用。
调试 DruidDataSource 找找setUsername看看， 没有发现，找父类 DruidAbstractDataSource， 发现了，
public void setUsername(String username) { if (this.inited) { throw new UnsupportedOperationException(); } else { this.username = username; } }
原来如此， inited 引起的。 加断点， 果然如此， 就是说， 如果init 过了， 再次setUsername 是会报错的！ 线程堆栈是这样的：
setUsername:1007, DruidAbstractDataSource (com.alibaba.druid.pool) invoke:-1, GeneratedMethodAccessor275 (sun.reflect) invoke:43, DelegatingMethodAccessorImpl (sun.reflect) invoke:498, Method (java.lang.reflect) setValue:320, JavaBeanBinder$BeanProperty (org.springframework.boot.context.properties.bind) bind:79, JavaBeanBinder (org.springframework.boot.context.properties.bind) bind:62, JavaBeanBinder (org.springframework.boot.context.properties.bind) bind:54, JavaBeanBinder (org.springframework.boot.context.properties.bind) lambda$null$5:341, Binder (org.springframework.boot.context.properties.bind) apply:-1, 1216198248 (org.springframework.boot.context.properties.bind.Binder$$Lambda$109) accept:193, ReferencePipeline$3$1 (java.util.stream) tryAdvance:1359, ArrayList$ArrayListSpliterator (java.util) forEachWithCancel:126, ReferencePipeline (java.util.stream) copyIntoWithCancel:498, AbstractPipeline (java.util.stream) copyInto:485, AbstractPipeline (java.util.stream) wrapAndCopyInto:471, AbstractPipeline (java.util.stream) evaluateSequential:152, FindOps$FindOp (java.util.stream) evaluate:234, AbstractPipeline (java.util.stream) findFirst:464, ReferencePipeline (java.util.stream) lambda$bindBean$6:342, Binder (org.springframework.boot.context.properties.bind) get:-1, 397071633 (org.springframework.boot.context.properties.bind.Binder$$Lambda$108) withIncreasedDepth:441, Binder$Context (org.springframework.boot.context.properties.bind) withBean:427, Binder$Context (org.springframework.boot.context.properties.bind) access$400:381, Binder$Context (org.springframework.boot.context.properties.bind) bindBean:339, Binder (org.springframework.boot.context.properties.bind) bindObject:278, Binder (org.springframework.boot.context.properties.bind) bind:221, Binder (org.springframework.boot.context.properties.bind) bind:210, Binder (org.springframework.boot.context.properties.bind) bind:192, Binder (org.springframework.boot.context.properties.bind) bind:82, ConfigurationPropertiesBinder (org.springframework.boot.context.properties) bind:107, ConfigurationPropertiesBindingPostProcessor (org.springframework.boot.context.properties) postProcessBeforeInitialization:93, ConfigurationPropertiesBindingPostProcessor (org.springframework.boot.context.properties) applyBeanPostProcessorsBeforeInitialization:416, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support) initializeBean:1686, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support) initializeBean:407, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support) rebind:102, ConfigurationPropertiesRebinder (org.springframework.cloud.context.properties) rebind:84, ConfigurationPropertiesRebinder (org.springframework.cloud.context.properties) onApplicationEvent:128, ConfigurationPropertiesRebinder (org.springframework.cloud.context.properties) onApplicationEvent:50, ConfigurationPropertiesRebinder (org.springframework.cloud.context.properties) doInvokeListener:172, SimpleApplicationEventMulticaster (org.springframework.context.event) invokeListener:165, SimpleApplicationEventMulticaster (org.springframework.context.event) multicastEvent:139, SimpleApplicationEventMulticaster (org.springframework.context.event) publishEvent:400, AbstractApplicationContext (org.springframework.context.support) publishEvent:354, AbstractApplicationContext (org.springframework.context.support) refresh:65, ContextRefresher (org.springframework.cloud.context.refresh) handle:36, RefreshEventListener (org.springframework.cloud.endpoint.event) invoke:-1, GeneratedMethodAccessor286 (sun.reflect) invoke:43, DelegatingMethodAccessorImpl (sun.reflect) invoke:498, Method (java.lang.reflect) doInvoke:261, ApplicationListenerMethodAdapter (org.springframework.context.event) processEvent:180, ApplicationListenerMethodAdapter (org.springframework.context.event) onApplicationEvent:142, ApplicationListenerMethodAdapter (org.springframework.context.event) doInvokeListener:172, SimpleApplicationEventMulticaster (org.springframework.context.event) invokeListener:165, SimpleApplicationEventMulticaster (org.springframework.context.event) multicastEvent:139, SimpleApplicationEventMulticaster (org.springframework.context.event) publishEvent:400, AbstractApplicationContext (org.springframework.context.support) publishEvent:354, AbstractApplicationContext (org.springframework.context.support) receiveConfigInfo:125, NacosContextRefresher$1 (org.springframework.cloud.alibaba.nacos.refresh) run:188, CacheData$1 (com.alibaba.nacos.client.config.impl) safeNotifyListener:209, CacheData (com.alibaba.nacos.client.config.impl) checkListenerMd5:160, CacheData (com.alibaba.nacos.client.config.impl) run:505, ClientWorker$LongPollingRunnable (com.alibaba.nacos.client.config.impl) runWorker:1149, ThreadPoolExecutor (java.util.concurrent) run:624, ThreadPoolExecutor$Worker (java.util.concurrent) run:748, Thread (java.lang)
可以看到publishEvent ， 可以肯定的是 这个publishEvent 正是前面的 NacosContextRefresher.this.applicationContext.publishEvent 方法 ！！ （这堆栈好深啊！） 仔细观察堆栈，发现 有个rebind 方法，感觉好奇怪（ 后面发现问题就是这个引起的！！)
那第一次init 是什么时候呢？ 调试发现是dynamicSqlSessionFactory 方法的 return sessionFactory.getObject();
还是不清楚 咋回事。 问题可怎么解决呢？？
Oh my God!!!
上网一把搜索，无果！ 没见到同样问题的出现。 难道这个问题就我一个人碰到吗？ 难道nacos 就我一个人用吗？？？
查看 https://blog.csdn.net/qq_37859539/article/details/81592954 https://blog.csdn.net/JAdroid/article/details/80490679 https://github.com/alibaba/druid/issues/2507 ， 难道是 filter 的问题？
查看https://github.com/alibaba/nacos issue， 没有。。
不至于这么大的坑， 就一个人碰到吧！ 感觉是哪个哪个的版本 问题吧， druid 从 1.0.26 升级到了 1.1.5 ， 再次观察 setUsername 方法：
public void setUsername(String username) { if (!StringUtils.equals(this.username, username)) { if (this.inited) { throw new UnsupportedOperationException(); } else { this.username = username; } } }
我一下子就豁然开朗！
原来如此， 这里的这个判断是不可少的吧！ nacos 会每个30 s 就去获取配置， 然后rebind， 但是druid-1.0.26 rebind 就会报错， 报错有没有打印出来！ 我擦。 druid-1.1.5 就不会有这个问题了！检查其他方法， 发现都做了 !StringUtils.equals 判断。
升级就对了嘛！原来 nacos 并没有错， 30s 重新获取配置然后重新绑定都是正确的， 逻辑都是没有问题的！ 原来是 druid的 大坑！！
以上是关于记druid 在配置中心下的一个大坑的主要内容，如果未能解决你的问题，请参考以下文章
Atom编辑器折腾记_(15)JS代码片段补全(插件:javascript-snippets)
数据源组件druid filter的扩展机制及spring boot 环境下的几种配置方式
Druid 查询超时配置的探究 → DataSource 和 JdbcTemplate 的 queryTimeout 到底谁生效？