We are using airflow version 1.9 with celery executor. And we are observing that Airflow Scheduler is not honouring the "non_pooled_task_slot_count" config. We are using default setting which is set to 128. But we could schedule and run >128 tasks concurrently. >From code it seems that scheduler is re-initialising the open_slots with 128 >instead of setting the remaining left over slots. In jobs.py for pool, task_instances in pool_to_task_instances.items(): if not pool: # Arbitrary: # If queued outside of a pool, trigger no more than # non_pooled_task_slot_count per run open_slots = conf.getint('core', 'non_pooled_task_slot_count') Thanks, Raman Gupta