大家好，我是烤鴨：

? ? 踩坑實錄。一個某次上線導致的問題，并沒有改過什么代碼，只是重新上了一次包，沒上之前從來沒出過這個問題。最開始日志的報錯信息一直是?NoClassDefFoundError could not initialize class ,發現是?static 初始化 spring bean 失敗，導致類沒有加載成功。

1.? 報錯日志

ex.ToString().org.springframework.web.util.NestedServletException: Handler dispatch failed; nested exception is java.lang.NoClassDefFoundError: Could not initialize class com.etc.common.utils.SequenceKit ex.Message,Handler dispatch failed; nested exception is java.lang.NoClassDefFoundError: Could not initialize class com.etc.common.utils.SequenceKit ex.StackTrace,org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1006) ex.Source,java.lang.NoClassDefFoundError: Could not initialize class com.etc.common.utils.SequenceKit

2.? 代碼復現：

SequenceKit.java

package com.xxx.common.utils;import java.util.concurrent.atomic.AtomicInteger;import org.checkerframework.common.value.qual.StaticallyExecutable; import org.joda.time.DateTime; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.data.redis.core.RedisTemplate;import com.fasterxml.jackson.core.Versioned;public class SequenceKit {private static final Logger logger = LoggerFactory.getLogger(SequenceKit.class);public static final String TYPE_INCR = "INCR:";public static final RedisTemplate redisTemplate = SpringContextUtil.getBean("redisTemplate", RedisTemplate.class);/*** 根據指定業務前綴生成自增 number* @return*/public static String getBusinessSequenceDoc(String key) {String date = new DateTime().toString("yyyyMMddHHmmss");logger.info("redisTemplate{}"+redisTemplate);Long no = redisTemplate.opsForValue().increment(TYPE_INCR+key, 1);if(no == null ){logger.info("redis 連接失敗{}"+TYPE_INCR+key);String uuid = UUIDUtil.generate();return key+ "-" + date + "-" + uuid;}return key+ "-" + date + "-" + String.format("%06d", no);}} SpringContextUtil.java package com.xxx.common.utils;import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.stereotype.Component;/*** * @ClassName: SpringContextUtil* @Description: 靜態獲取Bean* @author gaogang* @date 2016年7月12日 下午4:21:26**/ @Component public class SpringContextUtil implements ApplicationContextAware {/** 當前IOC上下文環境*/private static ApplicationContext applicationContext; /** 設置當前上下文環境，此方法由spring自動裝配 (non-Javadoc)* * @see* org.springframework.context.ApplicationContextAware#setApplicationContext* (org.springframework.context.ApplicationContext)*/@Overridepublic void setApplicationContext(ApplicationContext applicationContext)throws BeansException {SpringContextUtil.applicationContext = applicationContext;}public static ApplicationContext getApplicationContext() {return applicationContext;}/*** * @Description 從spring容器獲取bean實例</br>* <font color='red'>注意，這里beanId是spring ioc中bean實例的名字,如果是注解掃描方式，沒有特意指定名稱，一般為類名，首字母小寫(java遵從駝峰命名規則)，如果有指定名稱，則為指定的bean名稱</font>* @param name lmk name,infact it's name in spring IOC* @return bean實例** @author wjggwm* @data 2016年8月25日 下午2:22:16*/public static Object getBean(String name) throws BeansException {return getApplicationContext().getBean(name);}/*** * @Description 從spring容器獲取bean實例</br>* <font color='red'>注意，這里beanId是spring ioc中bean實例的名字,如果是注解掃描方式，沒有特意指定名稱，一般為類名，首字母小寫(java遵從駝峰命名規則)，如果有指定名稱，則為指定的bean名稱</font>* @param name lmk name,infact it's name in spring IOC* @param requiredType lmk class類型* @return bean實例* @throws BeansException** @author wjggwm* @data 2017年1月5日 下午5:58:27*/public static <T> T getBean(String name, Class<T> requiredType) throws BeansException {return getApplicationContext().getBean(name, requiredType);}public static <T> T getBean(Class<T> requiredType) {return applicationContext.getBean(requiredType);}}

3.? 問題猜想

靜態變量初始化在springbean之前，導致獲取不到bean對象，報錯。

其實有點想不通，測試環境和線上已經運行那么多天，如果是這個問題，早就應該曝光了。

靜態變量的初始化是在調用的時候再賦值，也就是調用這個方法的?getBean的時候，項目早已經啟動成功，不存在拿不到bean的情況。

4.? 場景模擬

后來想模擬線上的場景，將靜態變量 = 一個拋異常的方法，類似下面。確實爆錯了，原因找到了，就是這個對象初始化失敗。

為了避免這個問題，做了一下修改：

5.? 根本原因分析

改完就不會報異常了么。如果場景一樣的話，還是會報的。再貼一段同時報錯信息的日志。是redis 相關的日志，好像有點意思，都是redis相關的。

2020-05-20 15:38:54.356 [TID:591.16551.15899603343206723] [DubboServerHandler-20.0.22.51:20886-thread-105] INFO [class:co m.etc.redis.RedisUtil | method:set | line:177] logInfo==> redis set 異常 org.springframework.data.redis.RedisSystemException: Unknown redis exception; nested exception is java.lang.IllegalStateException: Cannot connect, Event executor group is termin ated.at org.springframework.data.redis.FallbackExceptionTranslationStrategy.getFallback(FallbackExceptionTranslationStrategy.java:53)at org.springframework.data.redis.FallbackExceptionTranslationStrategy.translate(FallbackExceptionTranslationStrategy.java:43)at org.springframework.data.redis.connection.lettuce.LettuceConnection.convertLettuceAccessException(LettuceConnection.java:257)at org.springframework.data.redis.connection.lettuce.LettuceStringCommands.convertLettuceAccessException(LettuceStringCommands.java:718)at org.springframework.data.redis.connection.lettuce.LettuceStringCommands.setEx(LettuceStringCommands.java:227)at org.springframework.data.redis.connection.DefaultedRedisConnection.setEx(DefaultedRedisConnection.java:252)at org.springframework.data.redis.core.DefaultValueOperations$4.potentiallyUsePsetEx(DefaultValueOperations.java:230)at org.springframework.data.redis.core.DefaultValueOperations$4.doInRedis(DefaultValueOperations.java:223)at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:224)at org.springframework.data.redis.core.RedisTemplate.execute(RedisTemplate.java:184)at org.springframework.data.redis.core.AbstractOperations.execute(AbstractOperations.java:95)at org.springframework.data.redis.core.DefaultValueOperations.set(DefaultValueOperations.java:218)at com.etc.redis.RedisUtil.set(RedisUtil.java:170)at com.etc.service.credit.EtcCreditApplyRelationServiceImpl.createNewApplyOrder(EtcCreditApplyRelationServiceImpl.java:1089)at com.etc.service.credit.EtcCreditApplyRelationServiceImpl$$FastClassBySpringCGLIB$$d7d53003.invoke(<generated>)at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)at com.etc.service.credit.EtcCreditApplyRelationServiceImpl$$EnhancerBySpringCGLIB$$a874bba6.createNewApplyOrder(<generated>)at com.alibaba.dubbo.common.bytecode.Wrapper33.invokeMethod(Wrapper33.java)at com.alibaba.dubbo.rpc.proxy.javassist.JavassistProxyFactory$1.doInvoke(JavassistProxyFactory.java:47)at com.alibaba.dubbo.rpc.proxy.AbstractProxyInvoker.invoke(AbstractProxyInvoker.java:76)at com.alibaba.dubbo.config.invoker.DelegateProviderMetaDataInvoker.invoke(DelegateProviderMetaDataInvoker.java:52)at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:56)at com.alibaba.dubbo.rpc.filter.ExceptionFilter.invoke(ExceptionFilter.java:62)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke$original$Mxc753iz(MonitorFilter.java:75)at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke$original$Mxc753iz$accessor$LYrs6xRu(MonitorFilter.java)at com.alibaba.dubbo.monitor.support.MonitorFilter$auxiliary$Xy5iiuam.call(Unknown Source)at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:93)at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.filter.TimeoutFilter.invoke(TimeoutFilter.java:42)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.protocol.dubbo.filter.TraceFilter.invoke(TraceFilter.java:78)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.filter.ContextFilter.invoke(ContextFilter.java:72)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.filter.GenericFilter.invoke(GenericFilter.java:131)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.filter.ClassLoaderFilter.invoke(ClassLoaderFilter.java:38)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.filter.EchoFilter.invoke(EchoFilter.java:38)at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:72)at com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol$1.reply(DubboProtocol.java:103)at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.handleRequest(HeaderExchangeHandler.java:96)at com.alibaba.dubbo.remoting.exchange.support.header.HeaderExchangeHandler.received(HeaderExchangeHandler.java:172)at com.alibaba.dubbo.remoting.transport.DecodeHandler.received(DecodeHandler.java:51)at com.alibaba.dubbo.remoting.transport.dispatcher.ChannelEventRunnable.run(ChannelEventRunnable.java:80)at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)at java.lang.Thread.run(Thread.java:748) Caused by: java.lang.IllegalStateException: Cannot connect, Event executor group is terminated.at io.lettuce.core.AbstractRedisClient.initializeChannelAsync(AbstractRedisClient.java:254)at io.lettuce.core.cluster.RedisClusterClient.connectStatefulAsync(RedisClusterClient.java:658)at io.lettuce.core.cluster.RedisClusterClient.connectStateful(RedisClusterClient.java:635)at io.lettuce.core.cluster.RedisClusterClient.connectClusterImpl(RedisClusterClient.java:530)at io.lettuce.core.cluster.RedisClusterClient.connect(RedisClusterClient.java:339)at org.springframework.data.redis.connection.lettuce.ClusterConnectionProvider.getConnection(ClusterConnectionProvider.java:55)at org.springframework.data.redis.connection.lettuce.LettuceConnection.doGetAsyncDedicatedConnection(LettuceConnection.java:962)at org.springframework.data.redis.connection.lettuce.LettuceConnection.getDedicatedConnection(LettuceConnection.java:942)at org.springframework.data.redis.connection.lettuce.LettuceConnection.getConnection(LettuceConnection.java:903)at org.springframework.data.redis.connection.lettuce.LettuceStringCommands.getConnection(LettuceStringCommands.java:714)at org.springframework.data.redis.connection.lettuce.LettuceStringCommands.setEx(LettuceStringCommands.java:225)... 53 common frames omitted

我們順著報錯類找到源碼看一下。

protected <K, V, T extends RedisChannelHandler<K, V>> ConnectionFuture<T> initializeChannelAsync(ConnectionBuilder connectionBuilder) {SocketAddress redisAddress = connectionBuilder.socketAddress();if (clientResources.eventExecutorGroup().isShuttingDown()) {throw new IllegalStateException("Cannot connect, Event executor group is terminated.");}// }

我們看一下??eventExecutorGroup 的說明。內部操作的線程池。

/*** Returns the computation pool used for internal operations. Such tasks are periodic Redis Cluster and Redis Sentinel* topology updates and scheduling of connection reconnection by {@link io.lettuce.core.protocol.ConnectionWatchdog}.** @return the computation pool used for internal operations*/EventExecutorGroup eventExecutorGroup();

這個判斷 就是線程池對應的group是不是關閉了。那我們就看一下哪個地方調用了shutdown方法。有點多，先看默認的Default哪個吧。

一路找下去：

DefaultClientResources.shutdown() ——> AbstractRedisClient.shutdownAsync() ——>LettuceConnectionFactory.destroy()

最終找到了?LettuceConnectionFactory 實現了?DisposableBean.destroy()

看下 DisposableBean 的說明：由要在銷毀時釋放資源的bean實現的接口。將在單個銷毀對象時調用destroy方法。也支持在應用程序生命周期的驅動下，在關機時處理所有單例。

/** Copyright 2002-2018 the original author or authors.** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at** http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/package org.springframework.beans.factory;/*** Interface to be implemented by beans that want to release resources on destruction.* A {@link BeanFactory} will invoke the destroy method on individual destruction of a* scoped bean. An {@link org.springframework.context.ApplicationContext} is supposed* to dispose all of its singletons on shutdown, driven by the application lifecycle.** <p>A Spring-managed bean may also implement Java's {@link AutoCloseable} interface* for the same purpose. An alternative to implementing an interface is specifying a* custom destroy method, for example in an XML bean definition. For a list of all* bean lifecycle methods, see the {@link BeanFactory BeanFactory javadocs}.** @author Juergen Hoeller* @since 12.08.2003* @see InitializingBean* @see org.springframework.beans.factory.support.RootBeanDefinition#getDestroyMethodName()* @see org.springframework.beans.factory.config.ConfigurableBeanFactory#destroySingletons()* @see org.springframework.context.ConfigurableApplicationContext#close()*/ public interface DisposableBean {/*** Invoked by the containing {@code BeanFactory} on destruction of a bean.* @throws Exception in case of shutdown errors. Exceptions will get logged* but not rethrown to allow other beans to release their resources as well.*/void destroy() throws Exception;}

這只是一種猜想，redisTemplate 這個 bean被銷毀了(在項目shutdown的過程中)。

6.? 再翻日志

再往前翻翻日志，發現啟動了項目的時候，前一次的項目并沒有停掉，導致新上線的啟動失敗。

這也怪我，運維說啟動成功了，我看日志一直在刷，并沒有意識到這個問題。

2020-05-20 15:36:34.443 [TID:N/A] [main-EventThread] INFO [class:org.apache.curator.framework.state.ConnectionStateManage r | method:postState | line:237] logInfo==> State change: CONNECTED 2020-05-20 15:36:53.004 [TID:N/A] [main] INFO [class:io.netty.util.internal.logging.Slf4JLogger | method:info | line:101]logInfo==> Starting without optional epoll library 2020-05-20 15:36:53.007 [TID:N/A] [main] INFO [class:io.netty.util.internal.logging.Slf4JLogger | method:info | line:101]logInfo==> Starting without optional kqueue library 2020-05-20 15:36:53.361 [TID:N/A] [main] INFO [class:com.etc.service.xxx.WeimobServiceImpl | method:refreshAccessToken| line:234] logInfo==> 啟動刷新任務，開始執行時間：2020-05-20T16:39:16.724 2020-05-20 15:36:53.961 [TID:N/A] [main] INFO [class:com.etc.config.BeforeStartup | method:onApplicationEvent | line:33]logInfo==> onApplicationEvent！！！redisUtil=com.etc.redis.RedisUtil@4407b042 2020-05-20 15:36:54.910 [TID:N/A] [main] INFO [class:org.apache.juli.logging.DirectJDKLog | method:log | line:180] logInfo==> Starting ProtocolHandler ["http-nio-8096"] 2020-05-20 15:36:54.916 [TID:N/A] [main] ERROR [class:org.apache.juli.logging.DirectJDKLog | method:log | line:182] logInfo==> Failed to start connector [Connector[HTTP/1.1-8096]] org.apache.catalina.LifecycleException: Failed to start component [Connector[HTTP/1.1-8096]]at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:167)at org.apache.catalina.core.StandardService.addConnector(StandardService.java:225)at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.addPreviouslyRemovedConnectors(TomcatWebServer.java:256)at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.start(TomcatWebServer.java:198)at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.startWebServer(ServletWebServerApplicationContext.java:300)at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.finishRefresh(ServletWebServerApplicationContext.java:162)at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:553)at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:780)at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:412)at org.springframework.boot.SpringApplication.run(SpringApplication.java:333)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1277)at org.springframework.boot.SpringApplication.run(SpringApplication.java:1265)at com.etc.ApplyServiceApplication.main(ApplyServiceApplication.java:33)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:48)at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) Caused by: org.apache.catalina.LifecycleException: Protocol handler start failedat org.apache.catalina.connector.Connector.startInternal(Connector.java:1020)at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)... 21 common frames omitted Caused by: java.net.BindException: Address already in useat sun.nio.ch.Net.bind0(Native Method)at sun.nio.ch.Net.bind(Net.java:433)at sun.nio.ch.Net.bind(Net.java:425)at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)at org.apache.tomcat.util.net.NioEndpoint.bind(NioEndpoint.java:219)at org.apache.tomcat.util.net.AbstractEndpoint.start(AbstractEndpoint.java:1151)at org.apache.coyote.AbstractProtocol.start(AbstractProtocol.java:591)at org.apache.catalina.connector.Connector.startInternal(Connector.java:1018)... 22 common frames omitted 2020-05-20 15:36:54.921 [TID:N/A] [main] INFO [class:org.apache.juli.logging.DirectJDKLog | method:log | line:180] logInfo==> Pausing ProtocolHandler ["http-nio-8096"] 2020-05-20 15:36:54.922 [TID:N/A] [main] INFO [class:org.apache.juli.logging.DirectJDKLog | method:log | line:180] logInfo==> Stopping service [Tomcat] 2020-05-20 15:36:54.961 [TID:N/A] [main] INFO [class:org.apache.juli.logging.DirectJDKLog | method:log | line:180] logInfo==> The stop() method was called on component [StandardServer[-1]] after stop() had already been called. The second call will be ignored. 2020-05-20 15:36:54.962 [TID:N/A] [main] INFO [class:org.apache.juli.logging.DirectJDKLog | method:log | line:180] logInfo==> Stopping ProtocolHandler ["http-nio-8096"] 2020-05-20 15:36:54.962 [TID:N/A] [main] INFO [class:org.apache.juli.logging.DirectJDKLog | method:log | line:180] logInfo==> Destroying ProtocolHandler ["http-nio-8096"]

這些都是小問題，但是注意到日志里多了一行，有點麻煩的。停止方法被已經被調用了，這次就忽略了。

The stop() method was called on component [StandardServer[-1]] after stop() had already been called. The second call will be ignored。

是運維的停止腳本(kill pid) 導致觸發了第一次的stop方法么。如果這樣就說的通了，stop的時候，導致調用了 shutdown ，將 redisTemplate 從 工廠移除，從而靜態初始化失敗。這個也有一個問題，就是為什么 繼承 DisposableBean?那么多類，怎么就單獨移除了一個 RedistTemplate。

只能強行解釋一波了，項目由于某些原因沒有停下來(可能是有在執行任務的線程)，但是部分類已經觸發了 destory 方法，從而導致部分連接池、bean對象失效等問題。

7.? 解決方案

運維操作的時候，最好盯著日志，是不是真的停止和啟動了。

?

總結

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