Implement run priorities

docs/docs/concepts/tasks.md

@@ -427,6 +427,34 @@ retry:
 If one job of a multi-node task fails with retry enabled,
 `dstack` will stop all the jobs and resubmit the run.
 
+### Priority
+
+Be default, submitted runs are scheduled in the order they were submitted.
+When compute resources are limited, you may want to prioritize some runs over others.
+This can be done by specifying the [`priority`](../reference/dstack.yml/task.md) property in the run configuration:
+
+<div editor-title=".dstack.yml">
+
+```yaml
+type: task
+name: train
+
+python: "3.10"
+
+# Commands of the task
+commands:
+  - pip install -r fine-tuning/qlora/requirements.txt
+  - python fine-tuning/qlora/train.py
+
+priority: 50
+```
+
+</div>
+
+`dstack` tries to provision runs with higher priority first.
+Note that if a high priority run cannot be scheduled,
+it does not block other runs with lower priority from scheduling.
+
 --8<-- "docs/concepts/snippets/manage-fleets.ext"
 
 --8<-- "docs/concepts/snippets/manage-runs.ext"

src/dstack/_internal/core/models/configurations.py

@@ -23,6 +23,9 @@
 MAX_INT64 = 2**63 - 1
 SERVICE_HTTPS_DEFAULT = True
 STRIP_PREFIX_DEFAULT = True
+RUN_PRIOTIRY_MIN = 0
+RUN_PRIOTIRY_MAX = 100
+RUN_PRIORITY_DEFAULT = 0
 
 
 class RunConfigurationType(str, Enum):
@@ -221,14 +224,26 @@ class BaseRunConfiguration(CoreModel):
             )
         ),
     ] = None
-    # deprecated since 0.18.31; task, service -- no effect; dev-environment -- executed right before `init`
-    setup: CommandsList = []
     resources: Annotated[
         ResourcesSpec, Field(description="The resources requirements to run the configuration")
     ] = ResourcesSpec()
+    priority: Annotated[
+        Optional[int],
+        Field(
+            ge=RUN_PRIOTIRY_MIN,
+            le=RUN_PRIOTIRY_MAX,
+            description=(
+                f"The priority of the run, an integer between `{RUN_PRIOTIRY_MIN}` and `{RUN_PRIOTIRY_MAX}`."
+                " `dstack` tries to provision runs with higher priority first."
+                f" Defaults to `{RUN_PRIORITY_DEFAULT}`"
+            ),
+        ),
+    ] = None
     volumes: Annotated[
         List[Union[MountPoint, str]], Field(description="The volumes mount points")
     ] = []
+    # deprecated since 0.18.31; task, service -- no effect; dev-environment -- executed right before `init`
+    setup: CommandsList = []
 
     @validator("python", pre=True, always=True)
     def convert_python(cls, v, values) -> Optional[PythonVersion]:

src/dstack/_internal/server/background/tasks/process_submitted_jobs.py

@@ -93,11 +93,20 @@ async def _process_next_submitted_job():
         async with lock:
             res = await session.execute(
                 select(JobModel)
+                .join(JobModel.run)
                 .where(
                     JobModel.status == JobStatus.SUBMITTED,
                     JobModel.id.not_in(lockset),
                 )
-                .order_by(JobModel.last_processed_at.asc())
+                # Jobs are process in FIFO sorted by priority globally,
+                # thus runs from different project can "overtake" each other by using higher priorities.
+                # That's not a big problem as long as projects do not compete for the same compute resources.
+                # Jobs with lower priorities from other projects will be processed without major lag
+                # as long as new higher priority runs are not constantly submitted.
+                # TODO: Consider processing jobs from different projects fairly/round-robin
+                # Fully fair processing can be tricky to implement via the current DB queue as
+                # there can be many projects and we are limited by the max DB connections.
+                .order_by(RunModel.priority.desc(), JobModel.last_processed_at.asc())
                 .limit(1)
                 .with_for_update(skip_locked=True)
             )

src/dstack/_internal/server/migrations/versions/bca2fdf130bf_add_runmodel_priority.py

@@ -0,0 +1,34 @@
+"""Add RunModel.priority
+
+Revision ID: bca2fdf130bf
+Revises: 20166748b60c
+Create Date: 2025-05-14 15:24:21.269775
+
+"""
+
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "bca2fdf130bf"
+down_revision = "20166748b60c"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table("runs", schema=None) as batch_op:
+        batch_op.add_column(sa.Column("priority", sa.Integer(), nullable=True))
+    batch_op.execute("UPDATE runs SET priority = 0")
+    with op.batch_alter_table("runs", schema=None) as batch_op:
+        batch_op.alter_column("priority", nullable=False)
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table("runs", schema=None) as batch_op:
+        batch_op.drop_column("priority")
+
+    # ### end Alembic commands ###

src/dstack/_internal/server/models.py

@@ -348,6 +348,7 @@ class RunModel(BaseModel):
     resubmission_attempt: Mapped[int] = mapped_column(Integer, default=0)
     run_spec: Mapped[str] = mapped_column(Text)
     service_spec: Mapped[Optional[str]] = mapped_column(Text)
+    priority: Mapped[int] = mapped_column(Integer, default=0)
 
     jobs: Mapped[List["JobModel"]] = relationship(
         back_populates="run", lazy="selectin", order_by="[JobModel.replica_num, JobModel.job_num]"

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

@@ -16,7 +16,7 @@
     ServerClientError,
 )
 from dstack._internal.core.models.common import ApplyAction
-from dstack._internal.core.models.configurations import AnyRunConfiguration
+from dstack._internal.core.models.configurations import RUN_PRIORITY_DEFAULT, AnyRunConfiguration
 from dstack._internal.core.models.instances import (
     InstanceAvailability,
     InstanceOfferWithAvailability,
@@ -434,7 +434,12 @@ async def apply_plan(
     # FIXME: potentially long write transaction
     # Avoid getting run_model after update
     await session.execute(
-        update(RunModel).where(RunModel.id == current_resource.id).values(run_spec=run_spec.json())
+        update(RunModel)
+        .where(RunModel.id == current_resource.id)
+        .values(
+            run_spec=run_spec.json(),
+            priority=run_spec.configuration.priority,
+        )
     )
     run = await get_run_by_name(
         session=session,
@@ -495,6 +500,7 @@ async def submit_run(
             status=RunStatus.SUBMITTED,
             run_spec=run_spec.json(),
             last_processed_at=submitted_at,
+            priority=run_spec.configuration.priority,
         )
         session.add(run_model)
 
@@ -852,6 +858,13 @@ def _get_job_submission_cost(job_submission: JobSubmission) -> float:
 
 
 def _validate_run_spec_and_set_defaults(run_spec: RunSpec):
+    # This function may set defaults for null run_spec values,
+    # although most defaults are resolved when building job_spec
+    # so that we can keep both the original user-supplied value (null in run_spec)
+    # and the default in job_spec.
+    # If a property is stored in job_spec - resolve the default there.
+    # Server defaults are preferable over client defaults so that
+    # the defaults depend on the server version, not the client version.
     if run_spec.run_name is not None:
         validate_dstack_resource_name(run_spec.run_name)
     for mount_point in run_spec.configuration.volumes:
@@ -875,11 +888,14 @@ def _validate_run_spec_and_set_defaults(run_spec: RunSpec):
         raise ServerClientError(
             f"Maximum utilization_policy.time_window is {settings.SERVER_METRICS_TTL_SECONDS}s"
         )
+    if run_spec.configuration.priority is None:
+        run_spec.configuration.priority = RUN_PRIORITY_DEFAULT
     set_resources_defaults(run_spec.configuration.resources)
 
 
 _UPDATABLE_SPEC_FIELDS = ["repo_code_hash", "configuration"]
-_CONF_TYPE_TO_UPDATABLE_FIELDS = {
+_CONF_UPDATABLE_FIELDS = ["priority"]
+_TYPE_SPECIFIC_CONF_UPDATABLE_FIELDS = {
     "dev-environment": ["inactivity_duration"],
     # Most service fields can be updated via replica redeployment.
     # TODO: Allow updating other fields when rolling deployment is supported.
@@ -915,12 +931,9 @@ def _check_can_update_configuration(
         raise ServerClientError(
             f"Configuration type changed from {current.type} to {new.type}, cannot update"
         )
-    updatable_fields = _CONF_TYPE_TO_UPDATABLE_FIELDS.get(new.type)
-    if updatable_fields is None:
-        raise ServerClientError(
-            f"Can only update {', '.join(_CONF_TYPE_TO_UPDATABLE_FIELDS)} configurations."
-            f" Not {new.type}"
-        )
+    updatable_fields = _CONF_UPDATABLE_FIELDS + _TYPE_SPECIFIC_CONF_UPDATABLE_FIELDS.get(
+        new.type, []
+    )
     diff = diff_models(current, new)
     changed_fields = list(diff.keys())
     for key in changed_fields:

src/dstack/_internal/server/testing/common.py

@@ -262,6 +262,7 @@ async def create_run(
     run_spec: Optional[RunSpec] = None,
     run_id: Optional[UUID] = None,
     deleted: bool = False,
+    priority: int = 0,
 ) -> RunModel:
     if run_spec is None:
         run_spec = get_run_spec(
@@ -282,6 +283,7 @@ async def create_run(
         run_spec=run_spec.json(),
         last_processed_at=submitted_at,
         jobs=[],
+        priority=priority,
     )
     session.add(run)
     await session.commit()

src/dstack/api/server/_runs.py

@@ -186,6 +186,8 @@ def _get_run_spec_excludes(run_spec: RunSpec) -> Optional[Dict]:
         configuration_excludes["rate_limits"] = True
     if configuration.shell is None:
         configuration_excludes["shell"] = True
+    if configuration.priority is None:
+        configuration_excludes["priority"] = True
 
     if configuration_excludes:
         spec_excludes["configuration"] = configuration_excludes

src/tests/_internal/server/background/tasks/test_process_submitted_jobs.py

@@ -634,3 +634,63 @@ async def test_creates_new_instance_in_existing_fleet(self, test_db, session: As
         assert job.instance is not None
         assert job.instance.instance_num == 1
         assert job.instance.fleet_id == fleet.id
+
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize("test_db", ["sqlite", "postgres"], indirect=True)
+    async def test_picks_high_priority_jobs_first(self, test_db, session: AsyncSession):
+        project = await create_project(session)
+        user = await create_user(session)
+        repo = await create_repo(
+            session=session,
+            project_id=project.id,
+        )
+        instance = await create_instance(
+            session=session,
+            project=project,
+            status=InstanceStatus.IDLE,
+        )
+        run1 = await create_run(
+            session=session,
+            project=project,
+            repo=repo,
+            user=user,
+            priority=10,
+        )
+        job1 = await create_job(
+            session=session,
+            run=run1,
+            instance_assigned=True,
+            instance=instance,
+        )
+        run2 = await create_run(
+            session=session,
+            project=project,
+            repo=repo,
+            user=user,
+            priority=0,
+        )
+        job2 = await create_job(
+            session=session, run=run2, instance_assigned=True, instance=instance
+        )
+        run3 = await create_run(
+            session=session,
+            project=project,
+            repo=repo,
+            user=user,
+            priority=100,
+        )
+        job3 = await create_job(
+            session=session,
+            run=run3,
+            instance_assigned=True,
+            instance=instance,
+        )
+        await process_submitted_jobs()
+        await session.refresh(job3)
+        assert job3.status == JobStatus.PROVISIONING
+        await process_submitted_jobs()
+        await session.refresh(job1)
+        assert job1.status == JobStatus.PROVISIONING
+        await process_submitted_jobs()
+        await session.refresh(job2)
+        assert job2.status == JobStatus.PROVISIONING

src/tests/_internal/server/routers/test_runs.py

@@ -124,6 +124,7 @@ def get_dev_env_run_plan_dict(
             "reservation": None,
             "fleets": None,
             "tags": None,
+            "priority": 0,
         },
         "configuration_path": "dstack.yaml",
         "profile": {
@@ -284,6 +285,7 @@ def get_dev_env_run_dict(
                 "reservation": None,
                 "fleets": None,
                 "tags": None,
+                "priority": 0,
             },
             "configuration_path": "dstack.yaml",
             "profile": {