Add warning/error if object store memory exceeds available memory (#4893)

* exclude

* format

* add warning

* hatch

* reduce mem usage

* reduce object store mem

* set obj mem

python/ray/tests/test_actor.py

@@ -506,7 +506,11 @@ def test_resource_assignment(shutdown_only):
     """Test to make sure that we assign resource to actors at instantiation."""
     # This test will create 16 actors. Declaring this many CPUs initially will
     # speed up the test because the workers will be started ahead of time.
-    ray.init(num_cpus=16, num_gpus=1, resources={"Custom": 1})
+    ray.init(
+        num_cpus=16,
+        num_gpus=1,
+        resources={"Custom": 1},
+        object_store_memory=int(10**8))
 
     class Actor(object):
         def __init__(self):
@@ -1262,7 +1266,7 @@ def test_actors_and_tasks_with_gpus(ray_start_cluster):
 def test_actors_and_tasks_with_gpus_version_two(shutdown_only):
     # Create tasks and actors that both use GPUs and make sure that they
     # are given different GPUs
-    ray.init(num_cpus=10, num_gpus=10)
+    ray.init(num_cpus=10, num_gpus=10, object_store_memory=int(10**8))
 
     @ray.remote(num_gpus=1)
     def f():