Implement running jobs pipeline

contributing/PIPELINES.md

@@ -37,6 +37,55 @@ Brief checklist for implementing a new pipeline:
 8. Register the pipeline in `PipelineManager` and hint fetch from services after commit via `pipeline_hinter.hint_fetch(Model.__name__)`.
 9. Add minimum tests: fetch eligibility/order, successful unlock path, stale lock token path, and related lock contention retry path.
 
+## Typical worker structure
+
+Most workers are easiest to reason about when `process()` is split into three phases:
+
+1. Load/refetch: open a short DB session, refetch the locked main row by `id + lock_token`, lock any required related rows, and gather any extra data needed for processing.
+2. Process: do the heavy work outside DB sessions and build result objects or update maps instead of mutating detached ORM models.
+3. Apply: open a short DB session, guard the main update by `id + lock_token`, resolve time placeholders, apply related updates, emit events, and unlock rows.
+
+A dedicated context object is often useful for the load step when the worker needs multiple loaded models, related lock metadata, or derived values that should be passed cleanly into processing and apply. For very small pipelines, a direct load -> process -> apply flow may still be clearer.
+
+Workers can share one context type and one apply function across all states even if the processing logic differs by state:
+
+```python
+async def process(item):
+    context = await _load_process_context(item)
+    if context is None:
+        return
+    result = await _process_item(context)
+    await _apply_process_result(item, context, result)
+```
+
+Sometimes state-specific helpers are still the cleanest option, but they can still share a common apply phase if all states write results in the same general shape:
+
+```python
+async def process(item):
+    if item.status == Status.PENDING:
+        context = await _load_pending_context(item)
+    elif item.status == Status.RUNNING:
+        context = await _load_running_context(item)
+    else:
+        return
+    if context is None:
+        return
+    result = await _process_item(context)
+    await _apply_process_result(item, context, result)
+```
+
+If different states have materially different write-side behavior, different apply paths are fine as well. This commonly happens when one state does a normal guarded update while another does delete-or-cleanup work with different related updates:
+
+```python
+async def process(item):
+    if item.to_be_deleted:
+        await _process_to_be_deleted_item(item)
+    elif item.status == Status.SUBMITTED:
+        await _process_submitted_item(item)
+```
+
+It's ok not to force all pipelines into one exact shape.
+
 ## Implementation patterns
 
 **Guarded apply by lock token**

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

@@ -5,6 +5,7 @@
 from dstack._internal.server.background.pipeline_tasks.fleets import FleetPipeline
 from dstack._internal.server.background.pipeline_tasks.gateways import GatewayPipeline
 from dstack._internal.server.background.pipeline_tasks.instances import InstancePipeline
+from dstack._internal.server.background.pipeline_tasks.jobs_running import JobRunningPipeline
 from dstack._internal.server.background.pipeline_tasks.jobs_terminating import (
     JobTerminatingPipeline,
 )
@@ -23,6 +24,7 @@ def __init__(self) -> None:
             ComputeGroupPipeline(),
             FleetPipeline(),
             GatewayPipeline(),
+            JobRunningPipeline(),
             JobTerminatingPipeline(),
             InstancePipeline(),
             PlacementGroupPipeline(),

src/dstack/_internal/server/background/pipeline_tasks/fleets.py

@@ -196,106 +196,23 @@ def __init__(
 
     @sentry_utils.instrument_named_task("pipeline_tasks.FleetWorker.process")
     async def process(self, item: PipelineItem):
-        async with get_session_ctx() as session:
-            res = await session.execute(
-                select(FleetModel)
-                .where(
-                    FleetModel.id == item.id,
-                    FleetModel.lock_token == item.lock_token,
-                )
-                .options(joinedload(FleetModel.project))
-                .options(
-                    selectinload(FleetModel.instances.and_(InstanceModel.deleted == False))
-                    .joinedload(InstanceModel.jobs)
-                    .load_only(JobModel.id),
-                )
-                .options(
-                    selectinload(
-                        FleetModel.runs.and_(RunModel.status.not_in(RunStatus.finished_statuses()))
-                    ).load_only(RunModel.status)
-                )
-            )
-            fleet_model = res.unique().scalar_one_or_none()
-            if fleet_model is None:
-                log_lock_token_mismatch(logger, item)
-                return
-
-            # Lock instance only if consolidation is needed.
-            locked_instance_ids: set[uuid.UUID] = set()
-            consolidation_fleet_spec = _get_fleet_spec_if_ready_for_consolidation(fleet_model)
-            consolidation_instances = None
-            if consolidation_fleet_spec is not None:
-                consolidation_instances = await _lock_fleet_instances_for_consolidation(
-                    session=session,
-                    item=item,
-                )
-                if consolidation_instances is None:
-                    return
-                locked_instance_ids = {instance.id for instance in consolidation_instances}
-
+        process_context = await _load_process_context(item)
+        if process_context is None:
+            return
         result = await _process_fleet(
-            fleet_model,
-            consolidation_fleet_spec=consolidation_fleet_spec,
-            consolidation_instances=consolidation_instances,
-        )
-        fleet_update_map = _FleetUpdateMap()
-        fleet_update_map.update(result.fleet_update_map)
-        set_processed_update_map_fields(fleet_update_map)
-        set_unlock_update_map_fields(fleet_update_map)
-        instance_update_rows = _build_instance_update_rows(
-            result.instance_id_to_update_map,
-            unlock_instance_ids=locked_instance_ids,
+            process_context.fleet_model,
+            consolidation_fleet_spec=process_context.consolidation_fleet_spec,
+            consolidation_instances=process_context.consolidation_instances,
         )
+        await _apply_process_result(item, process_context, result)
 
-        async with get_session_ctx() as session:
-            now = get_current_datetime()
-            resolve_now_placeholders(fleet_update_map, now=now)
-            resolve_now_placeholders(instance_update_rows, now=now)
-            res = await session.execute(
-                update(FleetModel)
-                .where(
-                    FleetModel.id == fleet_model.id,
-                    FleetModel.lock_token == fleet_model.lock_token,
-                )
-                .values(**fleet_update_map)
-                .returning(FleetModel.id)
-            )
-            updated_ids = list(res.scalars().all())
-            if len(updated_ids) == 0:
-                log_lock_token_changed_after_processing(logger, item)
-                if locked_instance_ids:
-                    await _unlock_fleet_locked_instances(
-                        session=session,
-                        item=item,
-                        locked_instance_ids=locked_instance_ids,
-                    )
-                # TODO: Clean up fleet.
-                return
-
-            if fleet_update_map.get("deleted"):
-                await session.execute(
-                    update(PlacementGroupModel)
-                    .where(PlacementGroupModel.fleet_id == item.id)
-                    .values(fleet_deleted=True)
-                )
-            if instance_update_rows:
-                await session.execute(
-                    update(InstanceModel),
-                    instance_update_rows,
-                )
-            if len(result.new_instance_creates) > 0:
-                await _create_missing_fleet_instances(
-                    session=session,
-                    fleet_model=fleet_model,
-                    new_instance_creates=result.new_instance_creates,
-                )
-            emit_fleet_status_change_event(
-                session=session,
-                fleet_model=fleet_model,
-                old_status=fleet_model.status,
-                new_status=fleet_update_map.get("status", fleet_model.status),
-                status_message=fleet_update_map.get("status_message", fleet_model.status_message),
-            )
+
+@dataclass
+class _ProcessContext:
+    fleet_model: FleetModel
+    consolidation_fleet_spec: Optional[FleetSpec]
+    consolidation_instances: Optional[list[InstanceModel]]
+    locked_instance_ids: set[uuid.UUID] = field(default_factory=set)
 
 
 class _FleetUpdateMap(ItemUpdateMap, total=False):
@@ -318,6 +235,83 @@ class _InstanceUpdateMap(ItemUpdateMap, total=False):
     id: uuid.UUID
 
 
+@dataclass
+class _ProcessResult:
+    fleet_update_map: _FleetUpdateMap = field(default_factory=_FleetUpdateMap)
+    instance_id_to_update_map: dict[uuid.UUID, _InstanceUpdateMap] = field(default_factory=dict)
+    new_instance_creates: list["_NewInstanceCreate"] = field(default_factory=list)
+
+
+class _NewInstanceCreate(TypedDict):
+    id: uuid.UUID
+    instance_num: int
+
+
+@dataclass
+class _MaintainNodesResult:
+    instance_id_to_update_map: dict[uuid.UUID, _InstanceUpdateMap] = field(default_factory=dict)
+    new_instance_creates: list[_NewInstanceCreate] = field(default_factory=list)
+    changes_required: bool = False
+
+    @property
+    def has_changes(self) -> bool:
+        return len(self.instance_id_to_update_map) > 0 or len(self.new_instance_creates) > 0
+
+
+async def _load_process_context(item: PipelineItem) -> Optional[_ProcessContext]:
+    async with get_session_ctx() as session:
+        fleet_model = await _refetch_locked_fleet(session=session, item=item)
+        if fleet_model is None:
+            log_lock_token_mismatch(logger, item)
+            return None
+
+        consolidation_fleet_spec = _get_fleet_spec_if_ready_for_consolidation(fleet_model)
+        consolidation_instances = None
+        if consolidation_fleet_spec is not None:
+            consolidation_instances = await _lock_fleet_instances_for_consolidation(
+                session=session,
+                item=item,
+            )
+            if consolidation_instances is None:
+                return None
+
+        return _ProcessContext(
+            fleet_model=fleet_model,
+            consolidation_fleet_spec=consolidation_fleet_spec,
+            consolidation_instances=consolidation_instances,
+            locked_instance_ids=(
+                set()
+                if consolidation_instances is None
+                else {i.id for i in consolidation_instances}
+            ),
+        )
+
+
+async def _refetch_locked_fleet(
+    session: AsyncSession,
+    item: PipelineItem,
+) -> Optional[FleetModel]:
+    res = await session.execute(
+        select(FleetModel)
+        .where(
+            FleetModel.id == item.id,
+            FleetModel.lock_token == item.lock_token,
+        )
+        .options(joinedload(FleetModel.project))
+        .options(
+            selectinload(FleetModel.instances.and_(InstanceModel.deleted == False))
+            .joinedload(InstanceModel.jobs)
+            .load_only(JobModel.id),
+        )
+        .options(
+            selectinload(
+                FleetModel.runs.and_(RunModel.status.not_in(RunStatus.finished_statuses()))
+            ).load_only(RunModel.status)
+        )
+    )
+    return res.unique().scalar_one_or_none()
+
+
 def _get_fleet_spec_if_ready_for_consolidation(fleet_model: FleetModel) -> Optional[FleetSpec]:
     if fleet_model.status == FleetStatus.TERMINATING:
         return None
@@ -398,27 +392,71 @@ async def _lock_fleet_instances_for_consolidation(
         return locked_instance_models
 
 
-@dataclass
-class _ProcessResult:
-    fleet_update_map: _FleetUpdateMap = field(default_factory=_FleetUpdateMap)
-    instance_id_to_update_map: dict[uuid.UUID, _InstanceUpdateMap] = field(default_factory=dict)
-    new_instance_creates: list["_NewInstanceCreate"] = field(default_factory=list)
-
-
-class _NewInstanceCreate(TypedDict):
-    id: uuid.UUID
-    instance_num: int
-
-
-@dataclass
-class _MaintainNodesResult:
-    instance_id_to_update_map: dict[uuid.UUID, _InstanceUpdateMap] = field(default_factory=dict)
-    new_instance_creates: list[_NewInstanceCreate] = field(default_factory=list)
-    changes_required: bool = False
+async def _apply_process_result(
+    item: PipelineItem,
+    context: _ProcessContext,
+    result: "_ProcessResult",
+) -> None:
+    fleet_update_map = _FleetUpdateMap()
+    fleet_update_map.update(result.fleet_update_map)
+    set_processed_update_map_fields(fleet_update_map)
+    set_unlock_update_map_fields(fleet_update_map)
+    instance_update_rows = _build_instance_update_rows(
+        result.instance_id_to_update_map,
+        unlock_instance_ids=context.locked_instance_ids,
+    )
 
-    @property
-    def has_changes(self) -> bool:
-        return len(self.instance_id_to_update_map) > 0 or len(self.new_instance_creates) > 0
+    async with get_session_ctx() as session:
+        now = get_current_datetime()
+        resolve_now_placeholders(fleet_update_map, now=now)
+        resolve_now_placeholders(instance_update_rows, now=now)
+        res = await session.execute(
+            update(FleetModel)
+            .where(
+                FleetModel.id == context.fleet_model.id,
+                FleetModel.lock_token == context.fleet_model.lock_token,
+            )
+            .values(**fleet_update_map)
+            .returning(FleetModel.id)
+        )
+        updated_ids = list(res.scalars().all())
+        if len(updated_ids) == 0:
+            log_lock_token_changed_after_processing(logger, item)
+            if context.locked_instance_ids:
+                await _unlock_fleet_locked_instances(
+                    session=session,
+                    item=item,
+                    locked_instance_ids=context.locked_instance_ids,
+                )
+            # TODO: Clean up fleet.
+            return
+
+        if fleet_update_map.get("deleted"):
+            await session.execute(
+                update(PlacementGroupModel)
+                .where(PlacementGroupModel.fleet_id == context.fleet_model.id)
+                .values(fleet_deleted=True)
+            )
+        if instance_update_rows:
+            await session.execute(
+                update(InstanceModel),
+                instance_update_rows,
+            )
+        if len(result.new_instance_creates) > 0:
+            await _create_missing_fleet_instances(
+                session=session,
+                fleet_model=context.fleet_model,
+                new_instance_creates=result.new_instance_creates,
+            )
+        emit_fleet_status_change_event(
+            session=session,
+            fleet_model=context.fleet_model,
+            old_status=context.fleet_model.status,
+            new_status=fleet_update_map.get("status", context.fleet_model.status),
+            status_message=fleet_update_map.get(
+                "status_message", context.fleet_model.status_message
+            ),
+        )
 
 
 async def _process_fleet(

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

@@ -238,8 +238,7 @@ async def process(self, item: InstancePipelineItem):
             process_context = await _process_terminating_item(item)
         if process_context is None:
             return
-        set_processed_update_map_fields(process_context.result.instance_update_map)
-        set_unlock_update_map_fields(process_context.result.instance_update_map)
+
         await _apply_process_result(
             item=item,
             instance_model=process_context.instance_model,
@@ -376,6 +375,9 @@ async def _apply_process_result(
     instance_model: InstanceModel,
     result: ProcessResult,
 ) -> None:
+    set_processed_update_map_fields(result.instance_update_map)
+    set_unlock_update_map_fields(result.instance_update_map)
+
     async with get_session_ctx() as session:
         if result.health_check_create is not None:
             session.add(InstanceHealthCheckModel(**result.health_check_create))