java - Tomcat 中的 Quartz 调度程序内存泄漏

Question

我使用 quartz 版本 2.2.2 和 Spring Boot 版本 1.3.1。它的行为正常，并且一切正常。但是当我试图关闭这个应用程序时，问题就出现了。日志显示存在内存泄漏...

我的 Quartz 配置；

org.quartz.scheduler.instanceName = my-app-jobs
org.quartz.scheduler.instanceId = AUTO
org.quartz.threadPool.threadCount=2
org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore
org.quartz.threadPool.class = org.quartz.simpl.SimpleThreadPool
org.quartz.scheduler.skipUpdateCheck = true

我有 2 个实现如下工作的类；

/**
 *
 * To Run Every 15 Minutes
 *
 */
public class MemoryDataUpdateJob implements Job {

    @Autowired
    private Dao dao;

    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException {
        Logger.info(getClass().getName(), "Scheduled Memory Data Update Job Started...");

        //Read Device Settings
        dao.readDeviceSettings();

        Logger.info(getClass().getName(), "Scheduled Memory Data Update Job Finished.");
    }

}

其他类也是类似的做不同的事情。

Scheduler Factory Bean如下；

@Bean
public SchedulerFactoryBean schedulerFactoryBean(
        JobFactory jobFactory,
        @Qualifier("MemoryDataUpdateJobTrigger") Trigger memoryDataUpdateJobTrigger,
        @Qualifier("MsgCountJobTrigger") Trigger msgCountJobTrigger) throws IOException {
    SchedulerFactoryBean factory = new SchedulerFactoryBean();
    factory.setJobFactory(jobFactory);
    factory.setQuartzProperties(quartzProperties());
    factory.setTriggers(memoryDataUpdateJobTrigger, msgCountJobTrigger);
    return factory;
}

我正在获取如下的 tomcat 日志；

19-Jan-2016 11:18:39.722 WARNING [localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [MyApp-1.0.0] appears to have started a thread named [schedulerFactoryBean_Worker-1] 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)

19-Jan-2016 11:18:39.722 WARNING [localhost-startStop-2] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [MyApp-1.0.0] appears to have started a thread named [schedulerFactoryBean_Worker-2] 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)

查看 quartz 文档并在属性中添加以下内容；

org.quartz.plugin.shutdownhook.class = org.quartz.plugins.management.ShutdownHookPlugin
org.quartz.plugin.shutdownhook.cleanShutdown = true

第一个线程消息消失了，但关于 worker-2 内存泄漏的第二个消息仍然存在。

但是在我的应用程序记录器中我看到了这样的东西；

[2016-01-19 11:18:39:681] [DEBUG] [schedulerFactoryBean_Worker-1] [org.quartz.simpl.SimpleThreadPool:612] - WorkerThread is shut down.

[2016-01-19 11:18:40:047] [DEBUG] [schedulerFactoryBean_Worker-2] [org.quartz.simpl.SimpleThreadPool:612] - WorkerThread is shut down.

[2016-01-19 11:18:40:049] [INFO ] [Quartz Shutdown-Hook schedulerFactoryBean] [org.quartz.plugins.management.ShutdownHookPlugin:126] - Shutting down Quartz...

这里有什么问题？为什么即使应用程序记录器显示线程已关闭，也会出现内存泄漏？

Answer 1

明白了。问题是 tomcat 正在关闭，但 quartz 作业正在运行。如果我们等待 1 秒之类的时间，它就会正常关闭。我们可以通过扩展 SchedulerFactoryBean 并覆盖它的 destroy 方法来实现。像下面这样的东西；

public class SchedulerFactoryBeanWithWait extends SchedulerFactoryBean {

@Override
public void destroy() throws SchedulerException {
    super.destroy();
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        logError(e);
    }
 }
}

和 bean 声明；

@Bean
public SchedulerFactoryBeanWithWait schedulerFactoryBeanWithWait (
        JobFactory jobFactory,
        @Qualifier("MemoryDataUpdateJobTrigger") Trigger memoryDataUpdateJobTrigger,
        @Qualifier("MsgCountJobTrigger") Trigger msgCountJobTrigger) throws IOException {
    SchedulerFactoryBeanWithWait factory = new SchedulerFactoryBeanWithWait ();
    factory.setJobFactory(jobFactory);
    factory.setQuartzProperties(quartzProperties());
    factory.setTriggers(memoryDataUpdateJobTrigger, msgCountJobTrigger);
    return factory;
}

这让它一直等到线程关闭。也许将来会对某人有所帮助。