[jbpm-issues] [JBoss JIRA] Updated: (JBPM-1454) Add some random when JobExecutorThread acquiring job

[Pavel Kadlec (JIRA)]

     [ https://jira.jboss.org/jira/browse/JBPM-1454?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Pavel Kadlec updated JBPM-1454:
-------------------------------

    Affects Version/s: jPDL 3.2.3
          Description: 
The method JobSession.getFirstAcquirableJob always acquires first available job. When using multithreaded JobExecutor, there is bigger probability that the JobExecutor threads takes the same job that will cause StaleObjectState exception.

I propose to add some random to the method JobSession.getFirstAcquirable.
Proposal solution

 public Job getFirstAcquirableJob(String lockOwner) {
    Job job = null;
    try {
      Query query = session.getNamedQuery("JobSession.getFirstAcquirableJob");
      query.setString("lockOwner", lockOwner);
      query.setTimestamp("now", new Date());
      query.setMaxResults(10); // TODO Magic number
      List results = query.list();
      int numResults = results.size();
      if (numResults > 0) {
    	  int whichResult = (int)(Thread.currentThread().getId() % numResults);
    	  job = (Job)results.get(whichResult);
      }
    } catch (Exception e) {
      log.error(e);
      throw new JbpmException("couldn't get acquirable jobs", e);
    }
    return job;
  }


> Add some random when JobExecutorThread acquiring job 
> -----------------------------------------------------
>
>                 Key: JBPM-1454
>                 URL: https://jira.jboss.org/jira/browse/JBPM-1454
>             Project: JBoss jBPM
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>    Affects Versions: jPDL 3.2.3
>            Reporter: Pavel Kadlec
>
> The method JobSession.getFirstAcquirableJob always acquires first available job. When using multithreaded JobExecutor, there is bigger probability that the JobExecutor threads takes the same job that will cause StaleObjectState exception.
> I propose to add some random to the method JobSession.getFirstAcquirable.
> Proposal solution
>  public Job getFirstAcquirableJob(String lockOwner) {
>     Job job = null;
>     try {
>       Query query = session.getNamedQuery("JobSession.getFirstAcquirableJob");
>       query.setString("lockOwner", lockOwner);
>       query.setTimestamp("now", new Date());
>       query.setMaxResults(10); // TODO Magic number
>       List results = query.list();
>       int numResults = results.size();
>       if (numResults > 0) {
>     	  int whichResult = (int)(Thread.currentThread().getId() % numResults);
>     	  job = (Job)results.get(whichResult);
>       }
>     } catch (Exception e) {
>       log.error(e);
>       throw new JbpmException("couldn't get acquirable jobs", e);
>     }
>     return job;
>   }

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