Sync from v0.13

tests/distributed/test_node_count.py

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+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import os
+
+import torch.distributed as dist
+
+from vllm.distributed.parallel_state import _node_count
+from vllm.distributed.utils import StatelessProcessGroup
+from vllm.utils.network_utils import get_ip, get_open_port
+
+if __name__ == "__main__":
+    dist.init_process_group(backend="gloo")
+
+    rank = dist.get_rank()
+    world_size = dist.get_world_size()
+
+    if rank == 0:
+        port = get_open_port()
+        ip = get_ip()
+        dist.broadcast_object_list([ip, port], src=0)
+    else:
+        recv = [None, None]
+        dist.broadcast_object_list(recv, src=0)
+        ip, port = recv
+
+    stateless_pg = StatelessProcessGroup.create(ip, port, rank, world_size)
+
+    for pg in [dist.group.WORLD, stateless_pg]:
+        test_result = _node_count(pg)
+
+        # Expected node count based on environment variable)
+        expected = int(os.environ.get("NUM_NODES", "1"))
+
+        assert test_result == expected, f"Expected {expected} nodes, got {test_result}"
+
+        if pg == dist.group.WORLD:
+            print(
+                f"Node count test passed! Got {test_result} nodes "
+                f"when using torch distributed!"
+            )
+        else:
+            print(
+                f"Node count test passed! Got {test_result} nodes "
+                f"when using StatelessProcessGroup!"
+            )