only infer reference point in global stopping if there is data

Summary: see title

Reviewed By: Balandat

Differential Revision: D55924472

ax/plot/pareto_utils.py

@@ -579,7 +579,7 @@ def _build_new_optimization_config(
 
 
 def infer_reference_point_from_experiment(
-    experiment: Experiment,
+    experiment: Experiment, data: Data
 ) -> List[ObjectiveThreshold]:
     """This functions is a wrapper around ``infer_reference_point`` to find the nadir
     point from the pareto front of an experiment. Aside from converting experiment
@@ -600,7 +600,8 @@ def infer_reference_point_from_experiment(
 
     # Reading experiment data.
     mb_reference = get_tensor_converter_model(
-        experiment=experiment, data=experiment.fetch_data()
+        experiment=experiment,
+        data=data,
     )
     obs_feats, obs_data, _ = _get_modelbridge_training_data(modelbridge=mb_reference)
 

ax/service/scheduler.py

@@ -450,10 +450,16 @@ def completion_criterion(self) -> Tuple[bool, str]:
                 and len(self.experiment.trials_by_status[TrialStatus.COMPLETED])
                 >= gss.min_trials
             ):
-                # We infer the nadir reference point to be used by the GSS.
-                self.__inferred_reference_point = infer_reference_point_from_experiment(
-                    self.experiment
-                )
+                # only infer reference point if there is data on the experiment.
+                data = self.experiment.fetch_data()
+                if not data.df.empty:
+                    # We infer the nadir reference point to be used by the GSS.
+                    self.__inferred_reference_point = (
+                        infer_reference_point_from_experiment(
+                            self.experiment,
+                            data=data,
+                        )
+                    )
 
             stop_optimization, global_stopping_msg = gss.should_stop_optimization(
                 experiment=self.experiment,

ax/service/tests/scheduler_test_utils.py

@@ -820,6 +820,40 @@ def test_inferring_reference_point(self) -> None:
             scheduler.run_n_trials(max_trials=10)
             mock_infer_rp.assert_called_once()
 
+    def test_inferring_reference_point_no_data(self) -> None:
+        init_test_engine_and_session_factory(force_init=True)
+        experiment = get_branin_experiment_with_multi_objective()
+        experiment.runner = self.runner
+        gs = self._get_generation_strategy_strategy_for_test(
+            experiment=experiment,
+            generation_strategy=self.sobol_GS_no_parallelism,
+        )
+
+        scheduler = Scheduler(
+            experiment=experiment,
+            generation_strategy=gs,
+            options=SchedulerOptions(
+                # Stops the optimization after 5 trials.
+                global_stopping_strategy=DummyGlobalStoppingStrategy(
+                    min_trials=0,
+                    trial_to_stop=5,
+                ),
+            ),
+            db_settings=self.db_settings,
+        )
+        empty_data = Data(
+            df=pd.DataFrame(
+                columns=["metric_name", "arm_name", "trial_index", "mean", "sem"]
+            )
+        )
+        with patch(
+            "ax.service.scheduler.infer_reference_point_from_experiment"
+        ) as mock_infer_rp, patch.object(
+            scheduler.experiment, "fetch_data", return_value=empty_data
+        ):
+            scheduler.run_n_trials(max_trials=1)
+            mock_infer_rp.assert_not_called()
+
     def test_global_stopping(self) -> None:
         gs = self._get_generation_strategy_strategy_for_test(
             experiment=self.branin_experiment,