Maybe I didn't get exactly what you need , but ...... you have 3 tasks, that needs to be unique. Also, you want to be sure that if a task crashes doesn't remain "hanged".
This should never happen with the scheduler .... the worst situation is that if a worker crashes (here "crashes" is it disconnects from the database) leaves the task status as running, but as soon as another scheduler checks if that one sends heartbeats, he removes the dead worker and requeue that task. If your task goes into timeout and it's a repeating task the best practice should be to raise the timeout. Assured this, you need to initialize the database if someone truncates the scheduler_task table, inserting the 3 records in one transaction. If you need to be sure, why all the hassle when you can "prepare" the task_name column as a unique value and then do db.update_or_insert(task_name==myuniquetaskname, **task_record) ? PS: code in models get executed every request. What if you have no users accessing the site and in the need to call initialize_task_queue ? Isn't it better to insert the values and then start the workers ? BTW: a task that needs to be running "forever" but can't be "launched" in two instances seems to suffer some design issues but hey, everyone needs to be able to do what he wants ;-)
