Fix multiprocessing to always use the spawn start method

cogment_lab/core.py

@@ -17,7 +17,7 @@
 import abc
 import copy
 import logging
-from typing import Awaitable, Callable, Generic, TypeVar
+from typing import Awaitable, Callable, Dict, Generic, TypeVar
 
 import cogment
 import numpy as np
@@ -30,14 +30,14 @@
 
 
 Action = TypeVar("Action")
-Actions = dict[str, Action]
+Actions = Dict[str, Action]
 
 Observation = TypeVar("Observation")
-Observations = dict[str, Observation]
+Observations = Dict[str, Observation]
 
-Rewards = dict[str, float]
+Rewards = Dict[str, float]
 
-Dones = dict[str, bool]
+Dones = Dict[str, bool]
 
 
 class State:

cogment_lab/envs/pettingzoo.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import logging
 from typing import Any, TypedDict
 

cogment_lab/process_manager.py

@@ -57,7 +57,7 @@ def __init__(
         user_id: str = "cogment_lab",
         torch_mode: bool = False,
         log_dir: str | None = None,
-        mp_method: str | None = None,
+        mp_method: str = "spawn",
         orchestrator_port: int = 9000,
         datastore_port: int = 9003,
     ):
@@ -67,8 +67,12 @@ def __init__(
             user_id (str, optional): User ID. Defaults to "cogment_lab".
             torch_mode (bool, optional): Whether to use PyTorch multiprocessing. Defaults to False.
             log_dir (str, optional): Directory to store logs. Defaults to "logs".
-            mp_method (str | None, optional): Multiprocessing method to use. Defaults to None.
+            mp_method (str, optional): Multiprocessing method to use. Defaults to "spawn". WARNING: Methods other than spawn are likely to not work. Use at your own risk.
         """
+        try:
+            mp.set_start_method(mp_method)
+        except RuntimeError:
+            pass
         self.processes: dict[ImplName, Process] = {}
         self.tasks: dict[ImplName, Task] = {}
 
@@ -132,7 +136,7 @@ def _add_process(
 
             p = TorchProcess(target=target, args=args)
         else:
-            p = self.mp_ctx.Process(target=target, args=args)  # type: ignore
+            p = self.mp_ctx.Process(target=target, args=args, name=f"cogment_lab_{name}")  # type: ignore
         p.start()
         self.processes[name] = p
 

cogment_lab/specs/action_space.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import gymnasium as gym
 
 from cogment_lab.generated.data_pb2 import PlayerAction  # type: ignore