Remove experimental.NoReturn (#7475)

python/ray/_raylet.pyx

@@ -91,7 +91,6 @@ from ray.exceptions import (
     ObjectStoreFullError,
     RayTimeoutError,
 )
-from ray.experimental.no_return import NoReturn
 from ray.utils import decode
 
 cimport cpython
@@ -998,7 +997,6 @@ cdef class CoreWorker:
                 c_owner_id,
                 c_owner_address)
 
-    # TODO: handle noreturn better
     cdef store_task_outputs(
             self, worker, outputs, const c_vector[CObjectID] return_ids,
             c_vector[shared_ptr[CRayObject]] *returns):
@@ -1016,10 +1014,6 @@ cdef class CoreWorker:
             if isinstance(output, ray.actor.ActorHandle):
                 raise Exception("Returning an actor handle from a remote "
                                 "function is not allowed).")
-            elif output is NoReturn:
-                serialized_objects.append(output)
-                data_sizes.push_back(0)
-                metadatas.push_back(string_to_buffer(b''))
             else:
                 context = worker.get_serialization_context()
                 serialized_object = context.serialize(output)
@@ -1036,11 +1030,7 @@ cdef class CoreWorker:
 
         for i, serialized_object in enumerate(serialized_objects):
             # A nullptr is returned if the object already exists.
-            if returns[0][i].get() == NULL:
-                continue
-            if serialized_object is NoReturn:
-                returns[0][i].reset()
-            else:
+            if returns[0][i].get() != NULL:
                 write_serialized_object(
                     serialized_object, returns[0][i].get().GetData())
 

python/ray/experimental/no_return.py

@@ -1,11 +0,0 @@
-class NoReturn:
-    """Do not store the return value in the object store.
-
-    If a task returns this object, then Ray will not store this object in the
-    object store. Calling `ray.get` on the task's return ObjectIDs may block
-    indefinitely unless the task manually stores an object for the
-    corresponding ObjectID.
-    """
-
-    def __init__(self):
-        raise TypeError("The `NoReturn` object should not be instantiated")

src/ray/core_worker/core_worker.cc

@@ -966,10 +966,8 @@ Status CoreWorker::AllocateReturnObjects(
         object_already_exists = !data_buffer;
       }
     }
-    // Leave the return object as a nullptr if there is no data or metadata.
-    // This allows the caller to prevent the core worker from storing an output
-    // (e.g., to support ray.experimental.no_return.NoReturn).
-    if (!object_already_exists && (data_buffer || metadatas[i])) {
+    // Leave the return object as a nullptr if the object already exists.
+    if (!object_already_exists) {
       return_objects->at(i) =
           std::make_shared<RayObject>(data_buffer, metadatas[i], contained_object_ids[i]);
     }