Add regression test for actor load balancing (#5224)

* Add regression test for actor load balancing

* Increase timeout

* Reduce number of nodes?

python/ray/tests/test_actor.py

@@ -905,6 +905,30 @@ def test_actor_load_balancing(ray_start_cluster):
     ray.get(results)
 
 
+@pytest.mark.skipif(
+    pytest_timeout is None,
+    reason="Timeout package not installed; skipping test that may hang.")
+@pytest.mark.timeout(10)
+def test_actor_lifetime_load_balancing(ray_start_cluster):
+    cluster = ray_start_cluster
+    cluster.add_node(num_cpus=0)
+    num_nodes = 3
+    for i in range(num_nodes):
+        cluster.add_node(num_cpus=1)
+    ray.init(redis_address=cluster.redis_address)
+
+    @ray.remote(num_cpus=1)
+    class Actor(object):
+        def __init__(self):
+            pass
+
+        def ping(self):
+            return
+
+    actors = [Actor.remote() for _ in range(num_nodes)]
+    ray.get([actor.ping.remote() for actor in actors])
+
+
 @pytest.mark.skipif(
     os.environ.get("RAY_USE_NEW_GCS") == "on",
     reason="Failing with new GCS API on Linux.")