refactor(rl): move grpcio guards to runtime entry points

pyproject.toml

@@ -333,9 +333,6 @@ ignore = [
 "__init__.py" = ["F401", "F403", "E402"]
 # E402: conditional-import guards (TYPE_CHECKING / is_package_available) must precede the imports they protect
 "src/lerobot/scripts/convert_dataset_v21_to_v30.py" = ["E402"]
-"src/lerobot/rl/actor.py" = ["E402"]
-"src/lerobot/rl/learner.py" = ["E402"]
-"src/lerobot/rl/learner_service.py" = ["E402"]
 "src/lerobot/policies/wall_x/**" = ["N801", "N812", "SIM102", "SIM108", "SIM210", "SIM211", "B006", "B007", "SIM118"] # Supprese these as they are coming from original Qwen2_5_vl code TODO(pepijn): refactor original
 
 [tool.ruff.lint.isort]

src/lerobot/rl/actor.py

@@ -46,18 +46,15 @@ For more details on the complete HILSerl training workflow, see:
 https://github.com/michel-aractingi/lerobot-hilserl-guide
 """
 
+from __future__ import annotations
+
 import logging
 import os
 import time
 from functools import lru_cache
 from queue import Empty
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
-from lerobot.utils.import_utils import require_package
-
-require_package("grpcio", extra="hilserl", import_name="grpc")
-
-import grpc
 import torch
 from torch import nn
 from torch.multiprocessing import Queue
@@ -69,16 +66,8 @@ from lerobot.processor import TransitionKey
 from lerobot.robots import so_follower  # noqa: F401
 from lerobot.teleoperators import gamepad, so_leader  # noqa: F401
 from lerobot.teleoperators.utils import TeleopEvents
-from lerobot.transport import services_pb2, services_pb2_grpc
-from lerobot.transport.utils import (
-    bytes_to_state_dict,
-    grpc_channel_options,
-    python_object_to_bytes,
-    receive_bytes_in_chunks,
-    send_bytes_in_chunks,
-    transitions_to_bytes,
-)
 from lerobot.utils.device_utils import get_safe_torch_device
+from lerobot.utils.import_utils import _grpc_available, require_package
 from lerobot.utils.process import ProcessSignalHandler
 from lerobot.utils.random_utils import set_seed
 from lerobot.utils.robot_utils import precise_sleep
@@ -91,6 +80,29 @@ from lerobot.utils.utils import (
     init_logging,
 )
 
+if TYPE_CHECKING or _grpc_available:
+    import grpc
+
+    from lerobot.transport import services_pb2, services_pb2_grpc
+    from lerobot.transport.utils import (
+        bytes_to_state_dict,
+        grpc_channel_options,
+        python_object_to_bytes,
+        receive_bytes_in_chunks,
+        send_bytes_in_chunks,
+        transitions_to_bytes,
+    )
+else:
+    grpc = None
+    services_pb2 = None
+    services_pb2_grpc = None
+    bytes_to_state_dict = None
+    grpc_channel_options = None
+    python_object_to_bytes = None
+    receive_bytes_in_chunks = None
+    send_bytes_in_chunks = None
+    transitions_to_bytes = None
+
 from .gym_manipulator import (
     make_processors,
     make_robot_env,
@@ -105,6 +117,7 @@ from .train_rl import TrainRLServerPipelineConfig
 
 @parser.wrap()
 def actor_cli(cfg: TrainRLServerPipelineConfig):
+    require_package("grpcio", extra="hilserl", import_name="grpc")
     cfg.validate()
     display_pid = False
     if not use_threads(cfg):

src/lerobot/rl/gym_manipulator.py

@@ -74,6 +74,7 @@ from lerobot.teleoperators import (
 from lerobot.teleoperators.teleoperator import Teleoperator
 from lerobot.teleoperators.utils import TeleopEvents
 from lerobot.utils.constants import ACTION, DONE, OBS_IMAGES, OBS_STATE, REWARD
+from lerobot.utils.import_utils import require_package
 from lerobot.utils.robot_utils import precise_sleep
 from lerobot.utils.utils import log_say
 
@@ -312,8 +313,6 @@ def make_robot_env(cfg: HILSerlRobotEnvConfig) -> tuple[gym.Env, Any]:
     # Check if this is a GymHIL simulation environment
     if cfg.name == "gym_hil":
         assert cfg.robot is None and cfg.teleop is None, "GymHIL environment does not support robot or teleop"
-        from lerobot.utils.import_utils import require_package
-
         require_package("gym-hil", extra="hilserl", import_name="gym_hil")
         import gym_hil  # noqa: F401
 

src/lerobot/rl/learner.py

@@ -44,6 +44,8 @@ For more details on the complete HILSerl training workflow, see:
 https://github.com/michel-aractingi/lerobot-hilserl-guide
 """
 
+from __future__ import annotations
+
 import logging
 import os
 import shutil
@@ -51,13 +53,8 @@ import time
 from concurrent.futures import ThreadPoolExecutor
 from pathlib import Path
 from pprint import pformat
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
-from lerobot.utils.import_utils import require_package
-
-require_package("grpcio", extra="hilserl", import_name="grpc")
-
-import grpc
 import torch
 from termcolor import colored
 from torch import nn
@@ -78,13 +75,6 @@ from lerobot.policies import make_policy, make_pre_post_processors
 from lerobot.robots import so_follower  # noqa: F401
 from lerobot.teleoperators import gamepad, so_leader  # noqa: F401
 from lerobot.teleoperators.utils import TeleopEvents
-from lerobot.transport import services_pb2_grpc
-from lerobot.transport.utils import (
-    MAX_MESSAGE_SIZE,
-    bytes_to_python_object,
-    bytes_to_transitions,
-    state_to_bytes,
-)
 from lerobot.utils.constants import (
     ACTION,
     CHECKPOINTS_DIR,
@@ -93,6 +83,7 @@ from lerobot.utils.constants import (
     TRAINING_STATE_DIR,
 )
 from lerobot.utils.device_utils import get_safe_torch_device
+from lerobot.utils.import_utils import _grpc_available, require_package
 from lerobot.utils.process import ProcessSignalHandler
 from lerobot.utils.random_utils import set_seed
 from lerobot.utils.utils import (
@@ -100,6 +91,24 @@ from lerobot.utils.utils import (
     init_logging,
 )
 
+if TYPE_CHECKING or _grpc_available:
+    import grpc
+
+    from lerobot.transport import services_pb2_grpc
+    from lerobot.transport.utils import (
+        MAX_MESSAGE_SIZE,
+        bytes_to_python_object,
+        bytes_to_transitions,
+        state_to_bytes,
+    )
+else:
+    grpc = None
+    services_pb2_grpc = None
+    MAX_MESSAGE_SIZE = None
+    bytes_to_python_object = None
+    bytes_to_transitions = None
+    state_to_bytes = None
+
 from .algorithms.base import RLAlgorithm
 from .algorithms.factory import make_algorithm
 from .buffer import ReplayBuffer
@@ -111,6 +120,7 @@ from .trainer import RLTrainer
 
 @parser.wrap()
 def train_cli(cfg: TrainRLServerPipelineConfig):
+    require_package("grpcio", extra="hilserl", import_name="grpc")
     if not use_threads(cfg):
         import torch.multiprocessing as mp
 

src/lerobot/rl/learner_service.py

@@ -18,13 +18,21 @@
 import logging
 import time
 from multiprocessing import Event, Queue
+from typing import TYPE_CHECKING
 
-from lerobot.utils.import_utils import require_package
+from lerobot.utils.import_utils import _grpc_available, require_package
 
-require_package("grpcio", extra="hilserl", import_name="grpc")
+if TYPE_CHECKING or _grpc_available:
+    from lerobot.transport import services_pb2, services_pb2_grpc
+    from lerobot.transport.utils import receive_bytes_in_chunks, send_bytes_in_chunks
 
-from lerobot.transport import services_pb2, services_pb2_grpc
-from lerobot.transport.utils import receive_bytes_in_chunks, send_bytes_in_chunks
+    _ServicerBase = services_pb2_grpc.LearnerServiceServicer
+else:
+    services_pb2 = None
+    services_pb2_grpc = None
+    receive_bytes_in_chunks = None
+    send_bytes_in_chunks = None
+    _ServicerBase = object
 
 from .queue import get_last_item_from_queue
 
@@ -32,7 +40,7 @@ MAX_WORKERS = 3  # Stream parameters, send transitions and interactions
 SHUTDOWN_TIMEOUT = 10
 
 
-class LearnerService(services_pb2_grpc.LearnerServiceServicer):
+class LearnerService(_ServicerBase):
     """
     Implementation of the LearnerService gRPC service
     This service is used to send parameters to the Actor and receive transitions and interactions from the Actor
@@ -48,6 +56,7 @@ class LearnerService(services_pb2_grpc.LearnerServiceServicer):
         interaction_message_queue: Queue,
         queue_get_timeout: float = 0.001,
     ):
+        require_package("grpcio", extra="hilserl", import_name="grpc")
         self.shutdown_event = shutdown_event
         self.parameters_queue = parameters_queue
         self.seconds_between_pushes = seconds_between_pushes

src/lerobot/utils/import_utils.py

@@ -132,6 +132,7 @@ _faker_available = is_package_available("faker")
 _pynput_available = is_package_available("pynput")
 _pygame_available = is_package_available("pygame")
 _qwen_vl_utils_available = is_package_available("qwen-vl-utils", import_name="qwen_vl_utils")
+_grpc_available = is_package_available("grpcio", import_name="grpc")
 _wallx_deps_available = (
     _transformers_available and _peft_available and _torchdiffeq_available and _qwen_vl_utils_available
 )