Grails Quartz Job has no Hibernate session after upgrade, causing LazyInitializationException

Question

I've upgraded a Grails 1.0.4 application to 1.1.1. After upgrading, I'm repeatedly getting Exceptions when executing my Quartz jobs (using Quartz plugin 0.4.1). The plugin is used to manually schedule jobs using Simple and Cron Triggers via a service (paraphrased code below):

class SchedulerService implements InitializingBean
{
    static scope = 'singleton'
    ...
    def schedule(def batch) {
        JobDetail job = new JobDetail(uniqueId, groupName, BatchJob.class, false, false, true)
        job.jobDataMap.put("batchId", batch.id)

        SimpleTrigger trigger = new SimpleTrigger(triggerId, triggerGroup, 0)

        SchedulerFactory factory = new SchedulerFactory()
        factory.initialize(properties)
        Scheduler scheduler = factory.getScheduler()

        scheduler.scheduleJob(job, trigger)
    }
    ...
}

My BatchJob job is set up as follows:

class BatchJob implements Job, InterruptableJob
{
    static triggers = {}
    void execute(JobExecutionContext context) {
        def batch = Batch.get(context.jobDetail.jobDataMap.getLongValue("batchId"))
        // the next line is "line 49" from the stack trace below
        def foo = batch.batchStatus.description
    }
}

Here's an abbreviated definition of Batch.groovy (domain):

class Batch
{
    BatchStatus batchStatus // relationship
}

However, when schedulerService.schedule() is invoked with an existing, saved Batch, I receive the following Exception:

org.hibernate.LazyInitializationException: could not initialize proxy - no Session
        at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:86)
        at org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsHibernateUtil.unwrapProxy(GrailsHibernateUtil.java:311)
        at org.codehaus.groovy.grails.orm.hibernate.cfg.GrailsHibernateUtil$unwrapProxy.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:40)
        ...
        <b>at BatchJob.execute(BatchJob.groovy:49)</b>
        ...

I've tried the following actions to fix this, but none have worked:

• I've specified static fetchMode = [batchStatus: 'eager'] on my Batch domain class
• I've used static mapping = { columns { batchStatus lazy:false }} on my Batch domain class
• I've tried using batch.attach() after calling Batch.get() in the Job

I can't use BatchJob.triggerNow() in this instance, because this is only one of a couple examples - the others are still scheduled by the service, but might be scheduled as a cron job or otherwise. I should mention that I did upgrade the Quartz plugin as well when upgrading Grails; the previous Quartz version was 0.4.1-SNAPSHOT (as opposed to the upgraded version, just 0.4.1).

How do I get Hibernate sessions to work correctly in these manually-triggered Quartz Jobs?

I've also sent this question to the grails-user mailing list, as for a more niche issue like this, the list seems to elicit a bit more response. I'll update this question with an answer if one comes out of there. Here's a link.

Answer 1

With the latest grails version (Grails 2.0.0) and maybe earlier versions, you can just wrap your call with this helper method:

class BatchJob implements Job, InterruptableJob
{
  static triggers = {}

  void execute(JobExecutionContext context) {
    Batch.withSession { sess ->
      def batch = Batch.get(context.jobDetail.jobDataMap.getLongValue("batchId"))
      def foo = batch.batchStatus.description
    }
  }
}

Answer 2

I think you can call attach() method to add session to the object passing to the scheduled job.

job.attach()

Answer 3

Check out jira issue 165 (http://jira.codehaus.org/browse/GRAILSPLUGINS-165) There are also clues in the Quartz Plugin (which you may like to check out) This code was used with the JMS plugin which seems to work well.

try

    import org.hibernate.FlushMode
    import org.hibernate.Session
    import org.springframework.orm.hibernate3.SessionFactoryUtils
    import org.springframework.orm.hibernate3.SessionHolder

    class BatchJob implements Job, InterruptableJob
    {
        static triggers = {}
        void execute(JobExecutionContext context) {
           Session session = null;   
           try { 
              session = SessionFactoryUtils.getSession(sessionFactory, false); 
           }
           // If not already bound the Create and Bind it! 
           catch (java.lang.IllegalStateException ex) { 
              session = SessionFactoryUtils.getSession(sessionFactory, true);  
              TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(session)); 
           }
          session.setFlushMode(FlushMode.AUTO);
          if( log.isDebugEnabled()) log.debug("Hibernate Session is bounded to Job thread");

        // Your Code!
        def batch = Batch.get(context.jobDetail.jobDataMap.getLongValue("batchId"))
        // the next line is "line 49" from the stack trace below
        def foo = batch.batchStatus.description



        try {
         SessionHolder sessionHolder = (SessionHolder) 
         TransactionSynchronizationManager.unbindResource(sessionFactory);
         if(!FlushMode.MANUAL.equals(sessionHolder.getSession().getFlushMode())) {
           sessionHolder.getSession().flush(); 
         }
         SessionFactoryUtils.closeSession(sessionHolder.getSession());
         if( log.isDebugEnabled()) log.debug("Hibernate Session is unbounded from Job thread and closed");
       }
       catch (Exception ex) { 
         ex.printStackTrace(); 
       }
   }
}

Hope this helps. It worked for me.