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.