Question

当我关闭Tomcat时，我观察到Spring WebApplicationContext的正确关闭和清理。但是，当我重新部署基于Spring的WAR（通过将新WAR复制到webapps）时，不会发生正常关闭。由于所有随后的资源泄漏，这对我来说是一个问题：

org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [] appears to have started a thread named [hz.hazelcast-swipe-instance.scheduled] but has failed to stop it. This is very likely to create a memory leak.
org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [] appears to have started a thread named [hz.hazelcast-swipe-instance.operation.thread-0] but has failed to stop it. This is very likely to create a memory leak.

......还有更多。我使用的是无XML配置，这是我的WebApplicationInitializer：

public class WebApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer
{
  @Override protected Class<?>[] getRootConfigClasses() {
    return new Class[] { WebSecurityConfig.class, WebMvcConfig.class };
  }
  @Override protected Class<?>[] getServletConfigClasses() { return null; }

  @Override protected String[] getServletMappings() { return new String[] { "/" }; }

  @Override public void onStartup(ServletContext ctx) throws ServletException {
    ctx.setInitParameter("spring.profiles.active", "production");
    super.onStartup(ctx);
  }
}

没有特定的配置来控制servlet上下文重新加载时的行为，我认为这应该是开箱即用的。

在继续servlet上下文重新加载过程之前，有没有办法让WebApplicationContext正常关闭？

我在Spring 4.0.5，Tomcat 7.0.54，Hazelcast 3.2.1，Hibernate 4.3.4.Final。

更新

我为ContextClosedEvent添加了一个Spring应用程序监听器，并打印了其调用的堆栈跟踪：

    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:333) [spring-context-4.0.6.RELEASE.jar:4.0.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:335) [spring-context-4.0.6.RELEASE.jar:4.0.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:880) [spring-context-4.0.6.RELEASE.jar:4.0.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:841) [spring-context-4.0.6.RELEASE.jar:4.0.6.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.destroy(FrameworkServlet.java:819) [spring-webmvc-4.0.6.RELEASE.jar:4.0.6.RELEASE]
    at org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1486) [catalina.jar:7.0.54]
    at org.apache.catalina.core.StandardWrapper.stopInternal(StandardWrapper.java:1847) [catalina.jar:7.0.54]
    at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232) [catalina.jar:7.0.54]
    at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5647) [catalina.jar:7.0.54]
    at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1575) [catalina.jar:7.0.54]
    at org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1564) [catalina.jar:7.0.54]

这表明Spring关闭发生在Servlet#destroy方法中。这是AbstractApplicationContext#close()的相关摘录：

        if (logger.isInfoEnabled()) {
            logger.info("Closing " + this);
        }

        LiveBeansView.unregisterApplicationContext(this);

        try {
            // Publish shutdown event.
            publishEvent(new ContextClosedEvent(this));
        }
        catch (Throwable ex) {
            logger.warn("Exception thrown from ApplicationListener handling ContextClosedEvent", ex);
        }
        // Stop all Lifecycle beans, to avoid delays during individual destruction.
        try {
            getLifecycleProcessor().onClose();
        }
        catch (Throwable ex) {
            logger.warn("Exception thrown from LifecycleProcessor on context close", ex);
        }

        // Destroy all cached singletons in the context's BeanFactory.
        destroyBeans();

        // Close the state of this context itself.
        closeBeanFactory();

        // Let subclasses do some final clean-up if they wish...
        onClose();

        synchronized (this.activeMonitor) {
            this.active = false;
        }

我从这个片段的开头看到了日志条目，我得到了我的ContextClosedEvent。我还看到了一个条目DefaultLifecycleProcessor - Stopping beans in phase 2147483647，它可能来自getLifecycleProcessor.onClose()行。似乎在下游发生了一些错误。可能会吞下一些例外。

更新2

根据要求，这是我配置Hazelcast的方式：

@Bean(destroyMethod="shutdown") public HazelcastInstance hazelcast() {
  final Config c = hzConfig();
  final JoinConfig join = c.getNetworkConfig().getJoin();
  join.getMulticastConfig().setEnabled(false);
  join.getTcpIpConfig().setEnabled(true);
  return getOrCreateHazelcastInstance(c);
}

hzConfig()是一种配置实例名称，组名称和密码，地图名称和地图索引的方法，所以我认为这不值得关注。

这是我的Hibernate SessionFactory配置：

@Bean
public LocalSessionFactoryBean sessionFactory() {
  final LocalSessionFactoryBean b = new LocalSessionFactoryBean();
  b.setDataSource(dataSource);
  b.setHibernateProperties(props(
      "hibernate.connection.release_mode", "on_close",
      "hibernate.id.new_generator_mappings", "true",
      "hibernate.hbm2ddl.auto", "update",
      "hibernate.order_inserts", "true",
      "hibernate.order_updates", "true",
      "hibernate.max_fetch_depth", "0",
      "hibernate.jdbc.fetch_size", "200",
      "hibernate.jdbc.batch_size", "50",
      "hibernate.jdbc.batch_versioned_data", "true",
      "hibernate.jdbc.use_streams_for_binary", "true",
      "hibernate.use_sql_comments", "true"
  ));
  return b;
}

Answer 1

在某些时候，您提到Logback存在NoClassDefFoundError。你通过删除这个依赖关系来解决这个问题，然后将问题转移到另一个类 - 一个Spring自己的类。

这可能意味着您所拥有的任何一个库都会对类加载器造成错误，或者Tomcat可能需要不对某些资源进行锁定的指令。请参阅here有关被锁定的Tomcat资源和<Context>设置的更多信息：在Tomcat的conf/context.xml antiResourceLocking="true"中添加{{1}}元素。

Answer 2

您是否尝试过为Tomcat上下文提升unloadDelay（默认为2000毫秒）？见http://tomcat.apache.org/tomcat-7.0-doc/config/context.html

UPDATE ：我发现你也遇到了回退问题，尝试注册这个监听器也许值得一试：

class LogbackShutdownListener implements ServletContextListener {

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        LoggerContext loggerContext = (LoggerContext)LoggerFactory.getILoggerFactory();
        System.out.println("Shutting down Logback context '" + loggerContext.getName() + "' for " + contextRootFor(event));
        loggerContext.stop();
    }

    @Override
    public void contextInitialized(ServletContextEvent event) {
        System.out.println("Logback context shutdown listener registered for " + contextRootFor(event));
    }

    private String contextRootFor(ServletContextEvent event) {
        return event.getServletContext().getContextPath();
    }

}

请务必在弹簧上下文加载器侦听器之前声明此侦听器，以便在关闭时上下文侦听器后调用。

更新2 ：也值得尝试注册另一个bean来手动关闭Hazelcast的东西（确保也从hazelcast bean中删除destroyMethod）：

@Component class HazelcastDestructor { @Autowired private HazelcastInstance instance; @PreDestroy public void shutdown() { try { instance.shutdown(); } catch (Exception e) { System.out.println("Hazelcast failed to shutdown(): " + e); throw e; } } }

更新3 ：出于好奇，您是否尝试过并行部署：http://www.javacodegeeks.com/2011/06/zero-downtime-deployment-and-rollback.html。可能的行为与重新加载相同的上下文不同。至少你应该能够懒惰地取消部署旧版本，看看是否有所作为。

Answer 3

当容器重启here时，悬空线程上存在类似问题。

在所有答案中，一个特别感兴趣的答案是霍华德 - 它显示了这些线程被清除的方式。

关于如何终止线程here，有一些很好的讨论和推理。

现在实现ServletContextListener并在contextDestroyed（）方法中处理这些线程：

    public class YourListener implements ServletContextListener{
        ....
        @Override
        public void contextDestroyed(ServletContextEvent event) {
            //Call the immolate method here
        }
    }

在WebApplicationInitilizer中将此侦听器注册为：

     ctx.addListener(new YourListener());

因此，当重新启动服务器时，会调用contextDestroyed方法，这会处理所有这些线程。

Answer 4

从Web App开发的角度来看，ServletContainer只能通知app的开始前和结束前的进程。它正在使用ServletContextListener。

在ServletContextListener

中配置web.xml

<listener>
    <listener-class>com.var.YourListener</listener-class>
</listener>

YourListener.java

public class YourListener implements ServletContextListener {

    public void contextInitialized(ServletContextEvent sce) {
        //initialization process
    }
    public void contextDestroyed(ServletContextEvent sce) {
        //destory process
    }
}

更新-XML Less

编程

@Override 
public void onStartup(ServletContext ctx) throws ServletException {

    ctx.addListener(new YourContextListener());

    ctx.setInitParameter("spring.profiles.active", "production");
    super.onStartup(ctx);
}

注释

@WebListener / @WebServletContextListener 
public class YourContextListener implements ServletContextListener {

    public void contextInitialized(ServletContextEvent servletContextEvent) {
    }

    public void contextDestroyed(ServletContextEvent servletContextEvent) {
    }
}

更新 - ShoutDown Hook In Spring

我从未在我的应用开发之前使用它，我们可以将shoutdownhook event注册到Spring的AbstractApplicationContext。我不确定你会不会好。

AbstractApplicationContext context = ...
context.registerShutdownHook();

Reference 1 Reference 2

WebApplicationContext没有在Servlet Context重新加载时关闭

更新

更新2

4 个答案: