Introduce flag to use pickle for serialization (#5805)

python/ray/services.py

@@ -1060,7 +1060,8 @@ def start_raylet(redis_address,
                  config=None,
                  include_java=False,
                  java_worker_options=None,
-                 load_code_from_local=False):
+                 load_code_from_local=False,
+                 use_pickle=False):
     """Start a raylet, which is a combined local scheduler and object manager.
 
     Args:
@@ -1092,6 +1093,7 @@ def start_raylet(redis_address,
         include_java (bool): If True, the raylet backend can also support
             Java worker.
         java_worker_options (str): The command options for Java worker.
+        use_pickle (bool): If True, use cloudpickle for serialization.
     Returns:
         ProcessInfo for the process that was started.
     """
@@ -1155,6 +1157,8 @@ def start_raylet(redis_address,
 
     if load_code_from_local:
         start_worker_command += " --load-code-from-local "
+    if use_pickle:
+        start_worker_command += " --use-pickle "
 
     command = [
         RAYLET_EXECUTABLE,