[RLlib] Issue with pickle versions (breaks rollout test cases in RLlib). (#11939)

rllib/rollout.py

@@ -8,10 +8,10 @@ from gym import wrappers as gym_wrappers
 import json
 import os
 from pathlib import Path
-import pickle
 import shelve
 
 import ray
+import ray.cloudpickle as cloudpickle
 from ray.rllib.env import MultiAgentEnv
 from ray.rllib.env.base_env import _DUMMY_AGENT_ID
 from ray.rllib.evaluation.worker_set import WorkerSet
@@ -118,7 +118,7 @@ class RolloutSaver:
             self._shelf.close()
         elif self._outfile and not self._use_shelve:
             # Dump everything as one big pickle:
-            pickle.dump(self._rollouts, open(self._outfile, "wb"))
+            cloudpickle.dump(self._rollouts, open(self._outfile, "wb"))
         if self._update_file:
             # Remove the temp progress file:
             self._get_tmp_progress_filename().unlink()
@@ -261,7 +261,7 @@ def run(args, parser):
     # Load the config from pickled.
     else:
         with open(config_path, "rb") as f:
-            config = pickle.load(f)
+            config = cloudpickle.load(f)
 
     # Set num_workers to be at least 2.
     if "num_workers" in config: