def _queue_task(self, task_key, args={}, priority=5):
"""
Adds a (root) task that is to be run.
Under the hood, the scheduler creates a task instance for the task, puts
it into the queue, and then tries to advance the queue.
"""
logger.info('Queued Task: %s - Args: %s' % (task_key, args))
task_instance = TaskInstance()
task_instance.task_key = task_key
task_instance.priority = priority
task_instance.args = simplejson.dumps(args)
task_instance.queued = datetime.now()
task_instance.status = STATUS_STOPPED
task_instance.save()
# queue the root task as the first work request. This lets the queue
# advancement logic to function the same for a root task or a subtask
task_instance.queue_worker_request(task_instance)
with self._queue_lock:
heappush(self._queue, [task_instance.compute_score(),task_instance])
# cache this task
self._active_tasks[task_instance.id] = task_instance
threads.deferToThread(self._schedule)
return task_instance
