Add FIXME

Author: r4victor

src/dstack/_internal/server/background/pipeline_tasks/instances/__init__.py

@@ -72,7 +72,7 @@ def __init__(
         workers_num: int = 20,
         queue_lower_limit_factor: float = 0.5,
         queue_upper_limit_factor: float = 2.0,
-        min_processing_interval: timedelta = timedelta(seconds=10),
+        min_processing_interval: timedelta = timedelta(seconds=15),
         lock_timeout: timedelta = timedelta(seconds=30),
         heartbeat_trigger: timedelta = timedelta(seconds=15),
     ) -> None:

src/dstack/_internal/server/services/fleets.py

@@ -799,6 +799,8 @@ async def delete_fleets(
         )
         instance_models_ids = list(res.scalars().unique().all())
         if len(instance_models_ids) != len(instances_ids):
+            # FIXME: In case of many instances, it can always fail.
+            # Try locking and waiting for all instances here until requests are queued for processing.
             msg = (
                 "Failed to delete fleets: fleet instances are being processed currently. Try again later."
                 if instance_nums is None