def queue_task(self, task_key, args={}, subtask_key=None):
"""
Queue a task to be run. All task requests come through this method. It saves their
information in the database. If the cluster has idle resources it will start the task
immediately, otherwise it will queue the task until it is ready.
"""
logger.info('Task:%s:%s - Queued: %s' % (task_key, subtask_key, args))
#create a TaskInstance instance and save it
task_instance = TaskInstance()
task_instance.task_key = task_key
task_instance.subtask_key = subtask_key
task_instance.args = simplejson.dumps(args)
task_instance.save()
#queue the task and signal attempt to start it
with self._lock_queue:
self._queue.append(task_instance)
self.advance_queue()
return task_instance
