[Placement Group]Add soft pack strategy (#10099)

python/ray/tests/test_placement_group.py

@@ -57,6 +57,51 @@ def test_placement_group_pack(ray_start_cluster):
     assert node_of_actor_1 == node_of_actor_2
 
 
+def test_placement_group_strict_pack(ray_start_cluster):
+    @ray.remote(num_cpus=2)
+    class Actor(object):
+        def __init__(self):
+            self.n = 0
+
+        def value(self):
+            return self.n
+
+    cluster = ray_start_cluster
+    num_nodes = 2
+    for _ in range(num_nodes):
+        cluster.add_node(num_cpus=4)
+    ray.init(address=cluster.address)
+
+    placement_group_id = ray.experimental.placement_group(
+        name="name", strategy="STRICT_PACK", bundles=[{
+            "CPU": 2
+        }, {
+            "CPU": 2
+        }])
+    actor_1 = Actor.options(
+        placement_group_id=placement_group_id,
+        placement_group_bundle_index=0).remote()
+    actor_2 = Actor.options(
+        placement_group_id=placement_group_id,
+        placement_group_bundle_index=1).remote()
+
+    print(ray.get(actor_1.value.remote()))
+    print(ray.get(actor_2.value.remote()))
+
+    # Get all actors.
+    actor_infos = ray.actors()
+
+    # Make sure all actors in counter_list are collocated in one node.
+    actor_info_1 = actor_infos.get(actor_1._actor_id.hex())
+    actor_info_2 = actor_infos.get(actor_2._actor_id.hex())
+
+    assert actor_info_1 and actor_info_2
+
+    node_of_actor_1 = actor_info_1["Address"]["NodeID"]
+    node_of_actor_2 = actor_info_2["Address"]["NodeID"]
+    assert node_of_actor_1 == node_of_actor_2
+
+
 def test_placement_group_spread(ray_start_cluster):
     @ray.remote(num_cpus=2)
     class Actor(object):