[RLlib; Offline RL] Make data pipeline better configurable and tuneable for users.

rllib/algorithms/algorithm_config.py

@@ -433,6 +433,9 @@ def __init__(self, algo_class: Optional[type] = None):
         self.input_read_method = "read_parquet"
         self.input_read_method_kwargs = {}
         self.input_read_schema = {}
+        self.map_batches_kwargs = {}
+        self.iter_batches_kwargs = {}
+        self.prelearner_class = None
         self.prelearner_module_synch_period = 10
         self.dataset_num_iters_per_learner = None
         self.input_config = {}
@@ -2373,6 +2376,9 @@ def offline_data(
         input_read_method=NotProvided,
         input_read_method_kwargs=NotProvided,
         input_read_schema=NotProvided,
+        map_batches_kwargs=NotProvided,
+        iter_batches_kwargs=NotProvided,
+        prelearner_class=NotProvided,
         prelearner_module_synch_period=NotProvided,
         dataset_num_iters_per_learner=NotProvided,
         input_config=NotProvided,
@@ -2403,10 +2409,12 @@ def offline_data(
                 offline data from `input_`. The default is `read_json` for JSON files.
                 See https://docs.ray.io/en/latest/data/api/input_output.html for more
                 info about available read methods in `ray.data`.
-            input_read_method_kwargs: kwargs for the `input_read_method`. These will be
-                passed into the read method without checking. If no arguments are passed
-                in the default argument `{'override_num_blocks': max(num_learners * 2,
-                2)}` is used.
+            input_read_method_kwargs: `kwargs` for the `input_read_method`. These will
+                be passed into the read method without checking. If no arguments are
+                passed in the default argument `{'override_num_blocks':
+                max(num_learners * 2, 2)}` is used. Use these `kwargs`` together with
+                the `map_batches_kwargs` and `iter_batches_kwargs` to tune the
+                performance of the data pipeline.
             input_read_schema: Table schema for converting offline data to episodes.
                 This schema maps the offline data columns to `ray.rllib.core.columns.
                 Columns`: {Columns.OBS: 'o_t', Columns.ACTIONS: 'a_t', ...}. Columns in
@@ -2415,6 +2423,27 @@ def offline_data(
                 schema used is `ray.rllib.offline.offline_data.SCHEMA`. If your data set
                 contains already the names in this schema, no `input_read_schema` is
                 needed.
+            map_batches_kwargs: `kwargs` for the `map_batches` method. These will be
+                passed into the `ray.data.Dataset.map_batches` method when sampling
+                without checking. If no arguments passed in the default arguments `{
+                'concurrency': max(2, num_learners), 'zero_copy_batch': True}` is
+                used. Use these `kwargs`` together with the `input_read_method_kwargs`
+                and `iter_batches_kwargs` to tune the performance of the data pipeline.
+            iter_batches_kwargs: `kwargs` for the `iter_batches` method. These will be
+                passed into the `ray.data.Dataset.iter_batches` method when sampling
+                without checking. If no arguments passed in the default arguments `{
+                'prefetch_batches': 2, 'local_buffer_shuffle_size':
+                train_batch_size_per_learner * 4}` is used. Use these `kwargs``
+                together with the `input_read_method_kwargs` and `map_batches_kwargs`
+                to tune the performance of the data pipeline.
+            prelearner_class: An optional `OfflinePreLearner` class that is used to
+                transform data batches in `ray.data.map_batches` used in the
+                `OfflineData` class to transform data from columns to batches that can
+                be used in the `Learner`'s `update` methods. Override the
+                `OfflinePreLearner` class and pass your dervied class in here, if you
+                need to make some further transformations specific for your data or
+                loss. The default is `None` which uses the base `OfflinePreLearner`
+                defined in `ray.rllib.offline.offline_prelearner`.
             prelearner_module_synch_period: The period (number of batches converted)
                 after which the `RLModule` held by the `PreLearner` should sync weights.
                 The `PreLearner` is used to preprocess batches for the learners. The
@@ -2470,6 +2499,8 @@ def offline_data(
             self.input_read_method_kwargs = input_read_method_kwargs
         if input_read_schema is not NotProvided:
             self.input_read_schema = input_read_schema
+        if prelearner_class is not NotProvided:
+            self.prelearner_class = prelearner_class
         if prelearner_module_synch_period is not NotProvided:
             self.prelearner_module_synch_period = prelearner_module_synch_period
         if dataset_num_iters_per_learner is not NotProvided:

rllib/algorithms/bc/bc.py

@@ -188,6 +188,9 @@ class (multi-/single-learner setup) and evaluation on
                 batch,
                 minibatch_size=self.config.train_batch_size_per_learner,
                 num_iters=self.config.dataset_num_iters_per_learner,
+                **self.offline_data.iter_batches_kwargs
+                if self.config.num_learners > 1
+                else {},
             )
 
             # Log training results.
@@ -217,7 +220,7 @@ class (multi-/single-learner setup) and evaluation on
         # Update weights - after learning on the local worker -
         # on all remote workers.
         with self.metrics.log_time((TIMERS, SYNCH_WORKER_WEIGHTS_TIMER)):
-            self.workers.sync_weights(
+            self.env_runner_group.sync_weights(
                 # Sync weights from learner_group to all EnvRunners.
                 from_worker_or_learner_group=self.learner_group,
                 policies=modules_to_update,

rllib/core/learner/learner.py

@@ -1143,7 +1143,8 @@ def update_from_iterator(
         *,
         timesteps: Optional[Dict[str, Any]] = None,
         minibatch_size: Optional[int] = None,
-        num_iters: int = 1,
+        num_iters: int = None,
+        **kwargs,
     ):
         self._check_is_built()
         minibatch_size = minibatch_size or 32
@@ -1162,8 +1163,7 @@ def _finalize_fn(batch: Dict[str, numpy.ndarray]) -> Dict[str, Any]:
         for batch in iterator.iter_batches(
             batch_size=minibatch_size,
             _finalize_fn=_finalize_fn,
-            prefetch_batches=2,
-            local_shuffle_buffer_size=minibatch_size * 10,
+            **kwargs,
         ):
             # Update the iteration counter.
             i += 1