Spring Boot应用运行15天后突发NullPointerException重启恢复求助

我的Spring Boot应用已连续稳定运行15天，突发NullPointerException错误，该错误发生在业务逻辑执行完成后的结果返回阶段。堆栈跟踪未直接指向业务代码，但重启服务后应用恢复正常。错误日志如下：

java.lang.NullPointerException: null
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:138) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:383) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:337) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.publishRequestHandledEvent(FrameworkServlet.java:1073) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at com.tenpay.iapay.wx.filters.RequestResponseLoggingFilter.doFilter(RequestResponseLoggingFilter.java:65) ~[iapay-wx-1.0.jar:1.0]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_292]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_292]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.6.jar:8.5.6]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_292]

问题定位 #

从堆栈轨迹可以明确，NPE发生在Spring的事件广播器调用监听器的环节，具体是请求处理完成后发布ServletRequestHandledEvent事件时触发。结合"长期稳定运行后突发、重启恢复"的特点，核心原因集中在以下几点：

1. 自定义监听器并发不安全：如果应用中有自定义的ApplicationListener实现，存在未同步的共享状态，高并发场景下可能导致监听器实例状态异常，最终出现null引用
2. 监听器被动态移除未处理并发：若有代码通过ApplicationContext动态移除监听器，但未考虑广播器正在迭代监听器列表的场景，会导致广播器持有的监听器引用变为null
3. Spring老版本bug：当前使用的Spring 4.3.4版本中，SimpleApplicationEventMulticaster的监听器列表迭代未做并发保护，当动态修改监听器列表时，容易出现NPE

解决方案 #

• 修复监听器线程安全：所有自定义监听器要么设计为无状态，要么对共享变量使用线程安全容器（如ConcurrentHashMap）或加锁同步
• 规范监听器注册方式：避免在运行时动态添加/移除监听器，尽量在应用启动阶段一次性完成注册；若必须动态操作，需通过ApplicationEventMulticaster的同步方法执行
• 升级Spring版本：升级到Spring 4.3.x分支的最新稳定版（如4.3.30.RELEASE），该版本修复了事件广播器的并发处理问题；条件允许的话直接升级到Spring 5.x系列
• 临时应急修复：若暂时无法升级Spring，可自定义SimpleApplicationEventMulticaster，在invokeListener方法中添加null检查，防止NPE导致请求失败

内容的提问来源于stack exchange，提问作者曾是然