Question

假设我有一个以这种方式配置的触发器：

<bean id="updateInsBBTrigger"         
    class="org.springframework.scheduling.quartz.CronTriggerBean">
    <property name="jobDetail" ref="updateInsBBJobDetail"/>
    <!--  run every morning at 5 AM  -->
    <property name="cronExpression" value="0 0 5 * * ?"/>
</bean>

触发器必须与另一个应用程序连接，如果有任何问题（如连接失败），它应该每10分钟重试一次任务五次或直到成功。有什么方法可以将触发器配置为像这样工作吗？

Answer 1

来源：Automatically Retry Failed Jobs in Quartz

如果你想让一个不断尝试的工作直到成功，你所要做的就是抛出一个带有标志的JobExecutionException，告诉调度程序在失败时再次触发它。以下代码显示了：

class MyJob implements Job {

    public MyJob() {
    }

    public void execute(JobExecutionContext context) throws JobExecutionException {

        try{
            //connect to other application etc
        }
        catch(Exception e){

            Thread.sleep(600000); //sleep for 10 mins

            JobExecutionException e2 = new JobExecutionException(e);
            //fire it again
            e2.setRefireImmediately(true);
            throw e2;
        }
    }
}

如果你想重试一定次数，它会变得有点复杂。您必须使用StatefulJob并在其JobDataMap中保存retryCounter，如果作业失败，您将增加该值。如果计数器超过了最大重试次数，则可以根据需要禁用该作业。

class MyJob implements StatefulJob {

    public MyJob() {
    }

    public void execute(JobExecutionContext context) throws JobExecutionException {
        JobDataMap dataMap = context.getJobDetail().getJobDataMap();
        int count = dataMap.getIntValue("count");

        // allow 5 retries
        if(count >= 5){
            JobExecutionException e = new JobExecutionException("Retries exceeded");
            //make sure it doesn't run again
            e.setUnscheduleAllTriggers(true);
            throw e;
        }


        try{
            //connect to other application etc

            //reset counter back to 0
            dataMap.putAsString("count", 0);
        }
        catch(Exception e){
            count++;
            dataMap.putAsString("count", count);
            JobExecutionException e2 = new JobExecutionException(e);

            Thread.sleep(600000); //sleep for 10 mins

            //fire it again
            e2.setRefireImmediately(true);
            throw e2;
        }
    }
}

Answer 2

我建议更灵活和可配置性，以便更好地在数据库中存储两个偏移： repeatOffset ，它会告诉你在应该重试作业多长时间以及 trialPeriodOffset 之后，它将保留作业所在的时间窗口的信息允许重新安排。然后你可以检索这两个参数，如（我假设你使用的是Spring）：

String repeatOffset = yourDBUtilsDao.getConfigParameter(..);
String trialPeriodOffset = yourDBUtilsDao.getConfigParameter(..);

然后代替记住计数器的工作，它需要记住initalAttempt：

Long initialAttempt = null;
initialAttempt = (Long) existingJobDetail.getJobDataMap().get("firstAttempt");

并执行以下检查：

long allowedThreshold = initialAttempt + Long.parseLong(trialPeriodOffset);
        if (System.currentTimeMillis() > allowedThreshold) {
            //We've tried enough, time to give up
            log.warn("The job is not going to be rescheduled since it has reached its trial period threshold");
            sched.deleteJob(jobName, jobGroup);
            return YourResultEnumHere.HAS_REACHED_THE_RESCHEDULING_LIMIT;
        }

最好为尝试的结果创建一个枚举，然后返回到您的核心工作流程申请如上。

然后构建重新安排时间：

Date startTime = null;
startTime = new Date(System.currentTimeMillis() + Long.parseLong(repeatOffset));

String triggerName = "Trigger_" + jobName;
String triggerGroup = "Trigger_" + jobGroup;

Trigger retrievedTrigger = sched.getTrigger(triggerName, triggerGroup);
if (!(retrievedTrigger instanceof SimpleTrigger)) {
            log.error("While rescheduling the Quartz Job retrieved was not of SimpleTrigger type as expected");
            return YourResultEnumHere.ERROR;
}

        ((SimpleTrigger) retrievedTrigger).setStartTime(startTime);
        sched.rescheduleJob(triggerName, triggerGroup, retrievedTrigger);
        return YourResultEnumHere.RESCHEDULED;

Answer 3

我建议像这样的实现在失败后恢复作业：

final JobDataMap jobDataMap = jobCtx.getJobDetail().getJobDataMap();
// the keys doesn't exist on first retry
final int retries = jobDataMap.containsKey(COUNT_MAP_KEY) ? jobDataMap.getIntValue(COUNT_MAP_KEY) : 0;

// to stop after awhile
if (retries < MAX_RETRIES) {
  log.warn("Retry job " + jobCtx.getJobDetail());

  // increment the number of retries
  jobDataMap.put(COUNT_MAP_KEY, retries + 1);

  final JobDetail job = jobCtx
      .getJobDetail()
      .getJobBuilder()
       // to track the number of retries
      .withIdentity(jobCtx.getJobDetail().getKey().getName() + " - " + retries, "FailingJobsGroup")
      .usingJobData(jobDataMap)
      .build();

  final OperableTrigger trigger = (OperableTrigger) TriggerBuilder
      .newTrigger()
      .forJob(job)
       // trying to reduce back pressure, you can use another algorithm
      .startAt(new Date(jobCtx.getFireTime().getTime() + (retries*100))) 
      .build();

  try {
    // schedule another job to avoid blocking threads
    jobCtx.getScheduler().scheduleJob(job, trigger);
  } catch (SchedulerException e) {
    log.error("Error creating job");
    throw new JobExecutionException(e);
  }
}

<强>为什么吗

它不会阻止Quartz Workers
它可以避免背压。使用setRefireIm立即，作业将立即被触发，并可能导致背压问题

失败时石英重试

3 个答案: