我正在使用 Spring Boot 1.5.9.RELEASE + Java 8 + Tomcat 9 + Jersey + Oracle 和我的应用程序的预定方法定义如下:

@Configuration
@EnableScheduling
public class ScheduleConfig implements SchedulingConfigurer {

    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        taskRegistrar.setScheduler(taskExecutor());
    }

    @Bean(destroyMethod = "shutdown")
    public Executor taskExecutor() {
        return Executors.newScheduledThreadPool(100);
    }
}

工作类别:

@Component
public class ClearCacheJob {



    @Scheduled(fixedRate = 3600000, initialDelay = 10000)
    public void clearErrorCodesCache() {
        try {
            logger.info("######## ClearCacheJob #########");
        } catch (Exception e) {
            logger.error("Exception in ClearCacheJob", e);
        }
    }

}

我还有一个类来注销 Oracle 驱动程序，如下所示:

@WebListener
public class ContainerContextClosedHandler implements ServletContextListener {

    private static final Logger logger = LoggerFactory.getLogger(ContainerContextClosedHandler.class);

    @Override
    public void contextInitialized(ServletContextEvent servletContextEvent) {
        logger.info("######### contextInitialized #########");
    }

    @Override
    public void contextDestroyed(ServletContextEvent servletContextEvent) {
        logger.info("######### contextDestroyed #########");
        Enumeration<Driver> drivers = DriverManager.getDrivers();
        while (drivers.hasMoreElements()) {
            Driver driver = drivers.nextElement();
            try {
                DriverManager.deregisterDriver(driver);
                logger.info(String.format("deregistering jdbc driver: %s", driver));
            } catch (SQLException e) {
                logger.info(String.format("Error deregistering driver %s", driver), e);
            }

        }
    }

}

但在停止 Tomcat 时出现以下错误:

WARNING [Thread-11] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [hai] 
appears to have started a thread named [Timer-0] but has failed to stop it. 
 This is very likely to create a memory leak. Stack trace of thread:
 java.lang.Object.wait(Native Method)
 java.lang.Object.wait(Unknown Source)
 java.util.TimerThread.mainLoop(Unknown Source)
 java.util.TimerThread.run(Unknown Source)

为什么会出现此错误，我该如何解决？

最佳答案

我想分享一些解决这个问题的根本原因分析。

For Oracle Users

解决方案 #1

您应该从 Tomcat 的 /lib 文件夹中删除您的 Oracle 驱动程序。 我遇到了同样的问题，它得到了解决。

注意:让Oracle驱动在/WEB-INF/lib文件夹中。

解决方案 #2

你可以通过 hibernate 线程来使用真正的hack。

@Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
    logger.info("######### contextDestroyed #########");
    Enumeration<Driver> drivers = DriverManager.getDrivers();
    while (drivers.hasMoreElements()) {
        Driver driver = drivers.nextElement();
        try {
            DriverManager.deregisterDriver(driver);
            logger.info(String.format("deregistering jdbc driver: %s", driver));
        } catch (SQLException e) {
            logger.info(String.format("Error deregistering driver %s", driver), e);
        }
    }
    try { Thread.sleep(2000L); } catch (Exception e) {} // Use this thread sleep
}

资源链接: Solution to “Tomcat can’t stop [Abandoned connection cleanup thread]”

解决方案 #3

Svetlin Zarev没有告诉任何人担心。这是tomcat的标准消息。他给出了如下根本原因分析:

This problem is occurred when an application has started ScheduledExecutor (but this will happen with any other Thread/TheadPool) and didn't shut it down on contextDestroyed. So check if you are shutting down your threads on application/server stop.

资源链接: Tomcat8 memory leak

解决方案 #4

Oracle 用户，这篇文章有多个答案:To prevent a memory leak, the JDBC Driver has been forcibly unregistered

For MySQL users

解决方案 #5

根本原因分析和解决方案:

The cleanup thread for abandoned connections in the NonRegisteringDriver class was refactored to have a static shutdown method. Memory was allocated but never released. If you encountered this leak problem, implement the context listener in your application with the AbandonedConnectionCleanupThread.shutdown() call in the contextDestroyed method.

This issue was found in applications running under the Tomcat application server, but it might have also applied to other application servers.

For example:

@WebListener
public class YourThreadsListener implements ServletContextListener {
   public void contextDestroyed(ServletContextEvent arg0) {
      try {
          AbandonedConnectionCleanupThread.shutdown();
      } catch (InterruptedException e) {
      }
   }
   ...
}

Note that if container does not support annotations, you add the description to web.xml:

<listener>
    <listener-class>user.package.YourThreadsListener</listener-class> 
</listener>

资源链接: https://docs.oracle.com/cd/E17952_01/connector-j-relnotes-en/news-5-1-23.html

关于java - Web 应用程序似乎启动了一个名为 [Timer-0] 的线程，但未能停止它，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48254517/