Implement async get for direct actor call (#6339)

python/ray/worker.py

@@ -61,6 +61,8 @@ LOCAL_MODE = 2
 
 ERROR_KEY_PREFIX = b"Error:"
 
+PY3 = sys.version_info.major >= 3
+
 # Logger for this module. It should be configured at the entry point
 # into the program using Ray. Ray provides a default configuration at
 # entry/init points.
@@ -1436,6 +1438,14 @@ def get(object_ids, timeout=None):
     """
     worker = global_worker
     worker.check_connected()
+
+    if PY3 and hasattr(
+            worker,
+            "core_worker") and worker.core_worker.current_actor_is_asyncio():
+        raise RayError("Using blocking ray.get inside async actor. "
+                       "This blocks the event loop. Please "
+                       "use `await` on object id with asyncio.gather.")
+
     with profiling.profile("ray.get"):
         is_individual_id = isinstance(object_ids, ray.ObjectID)
         if is_individual_id:
@@ -1548,6 +1558,13 @@ def wait(object_ids, num_returns=1, timeout=None):
     """
     worker = global_worker
 
+    if PY3 and hasattr(
+            worker,
+            "core_worker") and worker.core_worker.current_actor_is_asyncio():
+        raise RayError("Using blocking ray.wait inside async method. "
+                       "This blocks the event loop. Please use `await` "
+                       "on object id with asyncio.wait. ")
+
     if isinstance(object_ids, ObjectID):
         raise TypeError(
             "wait() expected a list of ray.ObjectID, got a single ray.ObjectID"