Currently we have a concept of resource pools for tasks, where there can be at most N instances of a task running at once. However, no such concept exists for DagRuns.
For example, you might have a requirement that two DAGs (with different dag_id) cannot run at the same time, so you might define a run_pool for these DAGs with size 1. Meaning only 1 DagRun may be in the RUNNING state at a time.
I am interested in hearing everyone's thoughts.