Split hp search methods (#6857)

* Split the run_hp_search by backend

* Unused import

src/transformers/integrations.py

@@ -3,7 +3,7 @@ import os
 
 import numpy as np
 
-from transformers.trainer_utils import PREFIX_CHECKPOINT_DIR, BestRun, HPSearchBackend
+from transformers.trainer_utils import PREFIX_CHECKPOINT_DIR, BestRun
 from transformers.utils import logging
 
 
@@ -83,7 +83,7 @@ def default_hp_search_backend():
         return "ray"
 
 
-def run_hp_search(trainer, n_trials, direction, kwargs):
+def run_hp_search_optuna(trainer, n_trials: int, direction: str, **kwargs) -> BestRun:
     def _objective(trial, checkpoint_dir=None):
         model_path = None
         if checkpoint_dir:
@@ -96,19 +96,33 @@ def run_hp_search(trainer, n_trials, direction, kwargs):
         if getattr(trainer, "objective", None) is None:
             metrics = trainer.evaluate()
             trainer.objective = trainer.compute_objective(metrics)
-            if trainer.hp_search_backend == HPSearchBackend.RAY:
-                trainer._tune_save_checkpoint()
-                ray.tune.report(objective=trainer.objective)
         return trainer.objective
 
-    if trainer.hp_search_backend == HPSearchBackend.OPTUNA:
     timeout = kwargs.pop("timeout", None)
     n_jobs = kwargs.pop("n_jobs", 1)
     study = optuna.create_study(direction=direction, **kwargs)
     study.optimize(_objective, n_trials=n_trials, timeout=timeout, n_jobs=n_jobs)
     best_trial = study.best_trial
-        best_run = BestRun(str(best_trial.number), best_trial.value, best_trial.params)
-    elif trainer.hp_search_backend == HPSearchBackend.RAY:
+    return BestRun(str(best_trial.number), best_trial.value, best_trial.params)
+
+
+def run_hp_search_ray(trainer, n_trials: int, direction: str, **kwargs) -> BestRun:
+    def _objective(trial, checkpoint_dir=None):
+        model_path = None
+        if checkpoint_dir:
+            for subdir in os.listdir(checkpoint_dir):
+                if subdir.startswith(PREFIX_CHECKPOINT_DIR):
+                    model_path = os.path.join(checkpoint_dir, subdir)
+        trainer.objective = None
+        trainer.train(model_path=model_path, trial=trial)
+        # If there hasn't been any evaluation during the training loop.
+        if getattr(trainer, "objective", None) is None:
+            metrics = trainer.evaluate()
+            trainer.objective = trainer.compute_objective(metrics)
+            trainer._tune_save_checkpoint()
+            ray.tune.report(objective=trainer.objective)
+        return trainer.objective
+
     # The model and TensorBoard writer do not pickle so we have to remove them (if they exists)
     # while doing the ray hp search.
     _tb_writer = trainer.tb_writer
@@ -137,12 +151,7 @@ def run_hp_search(trainer, n_trials, direction, kwargs):
                 "consider setting `keep_checkpoints_num=1`."
             )
     if "scheduler" in kwargs:
-            from ray.tune.schedulers import (
-                ASHAScheduler,
-                HyperBandForBOHB,
-                MedianStoppingRule,
-                PopulationBasedTraining,
-            )
+        from ray.tune.schedulers import ASHAScheduler, HyperBandForBOHB, MedianStoppingRule, PopulationBasedTraining
 
         # Check if checkpointing is enabled for PopulationBasedTraining
         if isinstance(kwargs["scheduler"], PopulationBasedTraining):
@@ -171,5 +180,4 @@ def run_hp_search(trainer, n_trials, direction, kwargs):
     best_trial = analysis.get_best_trial(metric="objective", mode=direction[:3])
     best_run = BestRun(best_trial.trial_id, best_trial.last_result["objective"], best_trial.config)
     trainer.tb_writer = _tb_writer
-
     return best_run

src/transformers/trainer.py

@@ -27,7 +27,8 @@ from .integrations import (
     is_ray_available,
     is_tensorboard_available,
     is_wandb_available,
-    run_hp_search,
+    run_hp_search_optuna,
+    run_hp_search_ray,
 )
 from .modeling_utils import PreTrainedModel
 from .optimization import AdamW, get_linear_schedule_with_warmup
@@ -884,7 +885,8 @@ class Trainer:
         self.hp_space = default_hp_space[backend] if hp_space is None else hp_space
         self.compute_objective = default_compute_objective if compute_objective is None else compute_objective
 
-        best_run = run_hp_search(self, n_trials, direction, kwargs)
+        run_hp_search = run_hp_search_optuna if backend == HPSearchBackend.OPTUNA else run_hp_search_ray
+        best_run = run_hp_search(self, n_trials, direction, **kwargs)
 
         self.hp_search_backend = None
         return best_run