[tune] move _SCHEDULERS to tune.schedulers and add all available schedulers (#11218)

Co-authored-by: Richard Liaw <rliaw@berkeley.edu>

python/ray/tune/schedulers/__init__.py

@@ -10,8 +10,6 @@ from ray.tune.schedulers.pbt import (PopulationBasedTraining,
 
 def create_scheduler(
         scheduler,
-        metric=None,
-        mode=None,
         **kwargs,
 ):
     """Instantiate a scheduler based on the given string.
@@ -20,45 +18,25 @@ def create_scheduler(
 
     Args:
         scheduler (str): The scheduler to use.
-        metric (str): The training result objective value attribute. Stopping
-            procedures will use this attribute.
-        mode (str): One of {min, max}. Determines whether objective is
-            minimizing or maximizing the metric attribute.
-        **kwargs: Additional parameters.
+        **kwargs: Scheduler parameters.
             These keyword arguments will be passed to the initialization
-            function of the chosen class.
+            function of the chosen scheduler.
     Returns:
         ray.tune.schedulers.trial_scheduler.TrialScheduler: The scheduler.
     Example:
-        >>> scheduler = tune.create_scheduler('pbt')
+        >>> scheduler = tune.create_scheduler('pbt', **pbt_kwargs)
     """
 
-    def _import_async_hyperband_scheduler():
-        from ray.tune.schedulers import AsyncHyperBandScheduler
-        return AsyncHyperBandScheduler
-
-    def _import_median_stopping_rule_scheduler():
-        from ray.tune.schedulers import MedianStoppingRule
-        return MedianStoppingRule
-
-    def _import_hyperband_scheduler():
-        from ray.tune.schedulers import HyperBandScheduler
-        return HyperBandScheduler
-
-    def _import_hb_bohb_scheduler():
-        from ray.tune.schedulers import HyperBandForBOHB
-        return HyperBandForBOHB
-
-    def _import_pbt_search():
-        from ray.tune.schedulers import PopulationBasedTraining
-        return PopulationBasedTraining
-
     SCHEDULER_IMPORT = {
-        "async_hyperband": _import_async_hyperband_scheduler,
-        "median_stopping_rule": _import_median_stopping_rule_scheduler,
-        "hyperband": _import_hyperband_scheduler,
-        "hb_bohb": _import_hb_bohb_scheduler,
-        "pbt": _import_pbt_search,
+        "fifo": FIFOScheduler,
+        "async_hyperband": AsyncHyperBandScheduler,
+        "asynchyperband": AsyncHyperBandScheduler,
+        "median_stopping_rule": MedianStoppingRule,
+        "medianstopping": MedianStoppingRule,
+        "hyperband": HyperBandScheduler,
+        "hb_bohb": HyperBandForBOHB,
+        "pbt": PopulationBasedTraining,
+        "pbt_replay": PopulationBasedTrainingReplay,
     }
     scheduler = scheduler.lower()
     if scheduler not in SCHEDULER_IMPORT:
@@ -66,8 +44,8 @@ def create_scheduler(
             f"Search alg must be one of {list(SCHEDULER_IMPORT)}. "
             f"Got: {scheduler}")
 
-    SchedulerClass = SCHEDULER_IMPORT[scheduler]()
-    return SchedulerClass(metric=metric, mode=mode, **kwargs)
+    SchedulerClass = SCHEDULER_IMPORT[scheduler]
+    return SchedulerClass(**kwargs)
 
 
 __all__ = [

python/ray/tune/tune.py

@@ -14,18 +14,10 @@ from ray.tune.registry import get_trainable_cls
 from ray.tune.syncer import wait_for_sync, set_sync_periods, SyncConfig
 from ray.tune.trial_runner import TrialRunner
 from ray.tune.progress_reporter import CLIReporter, JupyterNotebookReporter
-from ray.tune.schedulers import (HyperBandScheduler, AsyncHyperBandScheduler,
-                                 FIFOScheduler, MedianStoppingRule)
+from ray.tune.schedulers import FIFOScheduler
 
 logger = logging.getLogger(__name__)
 
-_SCHEDULERS = {
-    "FIFO": FIFOScheduler,
-    "MedianStopping": MedianStoppingRule,
-    "HyperBand": HyperBandScheduler,
-    "AsyncHyperBand": AsyncHyperBandScheduler,
-}
-
 try:
     class_name = get_ipython().__class__.__name__
     IS_NOTEBOOK = True if "Terminal" not in class_name else False
@@ -33,14 +25,6 @@ except NameError:
     IS_NOTEBOOK = False
 
 
-def _make_scheduler(args):
-    if args.scheduler in _SCHEDULERS:
-        return _SCHEDULERS[args.scheduler](**args.scheduler_config)
-    else:
-        raise TuneError("Unknown scheduler: {}, should be one of {}".format(
-            args.scheduler, _SCHEDULERS.keys()))
-
-
 def _check_default_resources_override(run_identifier):
     if not isinstance(run_identifier, str):
         # If obscure dtype, assume it is overridden.