Message "Data Calc Job FAILED TO COMPLETE. ... org.hibernate.LazyInitializationException: could not initialize proxy - no Session " logged hourly in the server.log file

Issue

• Message "Data Calc Job FAILED TO COMPLETE. ... org.hibernate.LazyInitializationException: could not initialize proxy - no Session " logged hourly in the server.log file
• Every hour, the following is logged in the server.log file:

18:00:08,613 ERROR [org.jboss.as.ejb3.invocation] (RHQScheduler_Worker-1) JBAS014134: EJB Invocation failed on component MeasurementOOBManagerBean for method public abstract void org.rhq.enterprise.server.measurement.MeasurementOOBManagerLocal.computeOOBsForLastHour(org.rhq.core.domain.auth.Subject,java.lang.Iterable): javax.ejb.EJBException: java.lang.RuntimeException: javax.ejb.EJBException: org.hibernate.LazyInitializationException: could not initialize proxy - no Session
...
    at org.rhq.enterprise.server.measurement.MeasurementOOBManagerLocal$$$view160.computeOOBsForLastHour(Unknown Source) [rhq-server.jar:4.12.0.JON330GA-redhat-4]
    at org.rhq.enterprise.server.scheduler.jobs.DataCalcJob.calculateOOBs(DataCalcJob.java:150) [rhq-server.jar:4.12.0.JON330GA-redhat-4]
    at org.rhq.enterprise.server.scheduler.jobs.DataCalcJob.executeJobCode(DataCalcJob.java:85) [rhq-server.jar:4.12.0.JON330GA-redhat-4]
    at org.rhq.enterprise.server.scheduler.jobs.AbstractStatefulJob.execute(AbstractStatefulJob.java:48) [rhq-server.jar:4.12.0.JON330GA-redhat-4]
    at org.quartz.core.JobRunShell.run(JobRunShell.java:202) [quartz-1.6.5.jar:1.6.5]
    at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:525) [quartz-1.6.5.jar:1.6.5]
Caused by: java.lang.RuntimeException: javax.ejb.EJBException: org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.rhq.enterprise.server.measurement.MeasurementOOBManagerBean.computeOOBsForLastHour(MeasurementOOBManagerBean.java:253) [rhq-server.jar:4.12.0.JON330GA-redhat-4]
...
    ... 29 more
Caused by: javax.ejb.EJBException: org.hibernate.LazyInitializationException: could not initialize proxy - no Session
...
18:00:08,621 ERROR [org.rhq.enterprise.server.scheduler.jobs.DataCalcJob] (RHQScheduler_Worker-1) Data Calc Job FAILED TO COMPLETE. Cause: javax.ejb.EJBException: java.lang.RuntimeException: javax.ejb.EJBException: org.hibernate.LazyInitializationException: could not initialize proxy - no Session
18:00:08,621 INFO  [org.rhq.enterprise.server.scheduler.jobs.DataCalcJob] (RHQScheduler_Worker-1) Data Calc Job FINISHED [8591]ms

• What is causing DataCalcJob to fail and what are implications?