[jboss-user] [EJB3] - Job manager/dispatcher pattern

[Bernard Labno]

Bernard Labno [https://community.jboss.org/people/blabno] created the discussion

"Job manager/dispatcher pattern"

To view the discussion, visit: https://community.jboss.org/message/822316#822316

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Hello

In my app there are some long running tasks that can be started from web front-end. Admin should see progress of those tasks in the same front-end.
What is the best approach to implement this?

Right now I have 1 ApplicationScoped JobManager and ~20 task executors running on separate JVM's (simple standalone apps). Those executors periodically (fast) pool JobManager for jobs through JAX-RS.
JobManager must know which job is executed by which executor so that it's not done twice. Also that information must be persistent (in case of JobManager crash/restart).
{code:lang=java}
public String assignJob(String executorId) {
    Job job = get1stUnassignedJobFromDB();
    job.setExecutorId(executorId);
    saveJobInDB(job);
    return job.getId();
}{code}

The problem is that sometimes executor 1 gets job A, the transaction doesn't get commited yet and the executor 2 also get's the same job.
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