Spring3.2.11与Quartz2.2.1整合时内存泄漏问题解决

Quartz是一款定时任务调度的开源框架,使用起来比较方便。并且Spring的support包对Quartz有集成。但是笔者在web应用使用的过程中却遇到了内存泄漏的问题。

问题的产生

笔者在使用Spring+Quartz的用法如下(熟悉Spring+Quartz的可以跳过直接看问题):

1.配置Scheduler工厂

<bean>
</bean>

2.编写Job的实现类QuartzJob,用来执行任务

//这里须继承spring的QuartzJobBean
public class QuartzJob extends QuartzJobBean {/**
    * 任务执行内容。
    */
    @Override
    protected void executeInternal(JobExecutionContext context) throws JobExecutionException {
        // 执行任务的代码
    }
}

3.将Scheduler工厂生产的scheduler注入到业务逻辑类中。这里注意,注入的其实是由schedulerFactory生产出来的scheduler实例(对Spring不熟悉的人会自然而然的认为注入的是schedulerFactory的实例,这是因为Spring的SchedulerFactoryBean实现了FactoryBean接口,所以注入的结果会是FactoryBean.getObject()获得的实例,题外话)。

<bean init-method="init" scope="singleton">
    <property>
      <ref bean="schedulerFactory"/>
    </property>
  </bean>

public class TaskServiceImpl {
    private Scheduler scheduler;/**
    * 由spring通过工厂注入,此实例为单例。
    * @param scheduler
    */
    public void setScheduler(Scheduler scheduler) {
        this.scheduler = scheduler;
    }

4.在业务逻辑类TaskServiceImpl中,使用scheduler执行任务。这里可以动态对任务执行增加、删除、重启等等操作。还有一个重要的特性是可以动态的改变Cron表达式,对任务的定时规则进行更改。

1    /**
 2      * 新增任务。
 3      * @param jobName
 4      * @param jobGroup
 5      * @param cron
 6      */
 7    public void addJob(String jobName, String jobGroup, String cron, String kindId) {
 8        try {
 9            if (StringUtil.isEmpty(jobName) || StringUtil.isEmpty(jobGroup) || StringUtil.isEmpty(cron)) {
10                throw new BusinessException("定时任务创建失败,参数为空");
11            }
12            JobDetail jobDetail = JobBuilder.newJob(QuartzJob.class).withIdentity(jobName, jobGroup).build();
13            jobDetail.getJobDataMap().put("JobKind", kindId);
14            //表达式调度构建器
15            CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule(cron);
16            //按新的cronExpression表达式构建一个新的trigger
17            CronTrigger trigger = TriggerBuilder.newTrigger().withIdentity(jobName, jobGroup).withSchedule(scheduleBuilder).build();
18            scheduler.scheduleJob(jobDetail, trigger);
19            log.info("新增定时任务,name:" + jobName + ",group:" + jobGroup + ",cron:" + cron);
20        } catch (SchedulerException e) {
21            // 对异常的处理
22        }
23    }

注意18行的scheduler是由Spring注入的。

这种用法在使用过程中没有问题,但在web应用在Tomcat6中热部署时出险了以下严重警告,如果忽略这种警告,在频繁的reload后会造成Tomcat 的 Permgen space OOM。

Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/feeder##1.5.0] appears to have started a thread named [scheduler_Worker-1] but has failed to stop it. This is very likely to create a memory leak.
Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/feeder##1.5.0] appears to have started a thread named [scheduler_Worker-2] but has failed to stop it. This is very likely to create a memory leak.
Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/feeder##1.5.0] appears to have started a thread named [scheduler_Worker-3] but has failed to stop it. This is very likely to create a memory leak.
Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/feeder##1.5.0] appears to have started a thread named [scheduler_Worker-4] but has failed to stop it. This is very likely to create a memory leak.
Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/feeder##1.5.0] appears to have started a thread named [scheduler_Worker-5] but has failed to stop it. This is very likely to create a memory leak.
Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/feeder##1.5.0] appears to have started a thread named [scheduler_Worker-6] but has failed to stop it. This is very likely to create a memory leak.
Jun 24, 2014 5:14:38 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads

问题的原因

究其原因是开启的scheduler_Worker线程没有关闭。但Spring的SchedulerFactoryBean实现了DisposableBean接口,表示web容器关闭时会执行destroy(),执行内容如下:

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