Merge branch 'optuna:master' into remove-jquery-extension

optuna/progress_bar.py

@@ -2,6 +2,7 @@
 from typing import Any
 from typing import Optional
 from typing import TYPE_CHECKING
+import warnings
 
 from tqdm.auto import tqdm
 
@@ -45,6 +46,9 @@ def __init__(
         n_trials: Optional[int] = None,
         timeout: Optional[float] = None,
     ) -> None:
+        if is_valid and n_trials is None and timeout is None:
+            warnings.warn("Progress bar won't be displayed because n_trials and timeout are None.")
+
         self._is_valid = is_valid and (n_trials or timeout) is not None
         self._n_trials = n_trials
         self._timeout = timeout

optuna/study/study.py

@@ -439,7 +439,6 @@ def objective(trial):
             RuntimeError:
                 If nested invocation of this method occurs.
         """
-
         _optimize(
             study=self,
             func=func,

tests/study_tests/test_study.py

@@ -978,6 +978,18 @@ def objective(trial: Trial) -> float:
     assert states == []
 
 
+def test_optimize_infinite_budget_progbar() -> None:
+    def terminate_study(study: Study, trial: FrozenTrial) -> None:
+        study.stop()
+
+    study = create_study()
+
+    with pytest.warns(UserWarning):
+        study.optimize(
+            func, n_trials=None, timeout=None, show_progress_bar=True, callbacks=[terminate_study]
+        )
+
+
 @pytest.mark.parametrize("storage_mode", STORAGE_MODES)
 def test_get_trials(storage_mode: str) -> None:
     with StorageSupplier(storage_mode) as storage: