Yep, *is_paused* does more than block new runs. The scheduler checks it directly when deciding which tasks to run next. That is what freezes downstream tasks today, and it is also why I would push back on "same is_paused but two buttons."
If you are suggesting that "Pause and drain" sets *is_paused=True* right away, those two checks still need a way to know "this one is a soft pause, let it keep going." That means adding a second flag anyway, just hidden behind the same name. And *is_paused* shows up in other places like backfill pause logic and asset triggered runs. Each of those would need checking to make sure a "soft paused" Dag still acts like an active one everywhere except the one spot it should not. From the PR, it avoids all that by keeping *is_paused=False* during drain, so every existing check keeps working as it should. It only adds new checks in a few places that decide whether to start a new run. Thanks & Regards, Amogh Desai On Tue, Sep 8, 2026 at 4:29 PM Jarek Potiuk <[email protected]> wrote: > I like the idea Amogh. I think **just changing** pause behaviour might not > be good idea for compatibility (someone might rely on it's current > behaviour). > > But maybe we could have different behaviour of two > different buttons/behaviour: "Pause" (current behaviour - stop current > tasks and it's downstream), "Pause and drain" - set the Dag to "paused" but > let the running dag_runs to continue until completion. > > It might however require some scheduler changes - I think currently > is_paused is used to select run-eligible tasks ? > > J. > > > On Tue, Sep 8, 2026 at 7:41 AM Amogh Desai <[email protected]> wrote: > > > Thanks for picking a 4-year-old issue. > > The ask itself makes sense. > > > > One design question that might eventually come up in this thread / PR is: > > why do we need a new persisted state > > instead of just changing what is_paused does? i.e: keep gating new run > > creation on is_paused, but stop freezing > > downstream tasks in created runs. That would get you graceful draining > > without a schema change or migration. > > > > From my reading, doing that would silently change the semantics of > > *is_paused*. Today, freezes downstream tasks in-flight. > > Some operators pause specifically to stop a run's progress, not just to > > block new ones. Folding drain behavior into *is_paused* > > might change that for everyone already relying on the current freeze + > > pause behavior, with no option to opt out, yes? > > Worth clarifying. > > > > Thanks & Regards, > > Amogh Desai > > > > > > On Sun, Sep 6, 2026 at 3:15 AM Dheeraj Turaga <[email protected]> > > wrote: > > > > > Hey Everyone, > > > > > > I wanted to start this discussion to get feedback on PR #72407, which > > > proposes adding a "draining" scheduling state to Airflow. > > > > > > The Problem > > > > > > Currently, pausing a DAG stops it mid-flight. While running tasks are > > > allowed to finish, queued and downstream tasks remain stranded until > the > > > DAG is unpaused. There is currently no native way to stop starting new > > runs > > > while allowing those already in flight to complete. > > > > > > This is a significant pain point during upgrades and maintenance. The > > > current workaround as described in the four-year-old Issue #22006 > > requires > > > users to manually rewrite every DAG schedule to None, wait for runs to > > > drain, and then restore the schedules afterward. This process is > invasive > > > and prone to error. > > > > > > Proposed Solution: The draining State > > > > > > The PR introduces a draining state that sits between active and paused. > > Key > > > behaviors include: > > > > > > - No New Scheduled Runs: The scheduler creates no new runs for a > > draining > > > DAG (including scheduled, asset-triggered, and partitioned/rollup > paths). > > > - Completion of In-Flight Runs: is_paused remains false during the > > drain, > > > meaning task instances in existing runs are still scheduled and finish > > > normally. > > > - Automatic Convergence: Once no unfinished runs remain, the > scheduler > > > automatically moves the DAG to the paused state and writes a > > > drain_completed audit log entry. > > > > > > The core property of this feature is that draining is transient, not a > > > third resting state; it always converges to paused. > > > > > > Implementation Details > > > > > > Explicit run creation via manual triggers, TriggerDagRunOperator, asset > > > materialization, or backfills remains allowed during draining, > mirroring > > > the behavior of a paused DAG. An earlier revision that blocked these > > > actions was reverted to ensure draining is not stricter than the state > it > > > converges into. > > > > > > Links: > > > > > > - PR: https://github.com/apache/airflow/pull/72407 > > > - Issue: https://github.com/apache/airflow/issues/22006 > > > > > > Thanks, > > > Dheeraj > > > > > >
