[Bug Fix] Fix address/port already in use error for deep_ep test (#20094)

Signed-off-by: yewentao256 <zhyanwentao@126.com>

tests/kernels/moe/deepep_utils.py

@@ -4,6 +4,7 @@ DeepEP test utilities
 """
 import dataclasses
 import importlib
+import os
 import traceback
 from typing import Callable, Optional
 
@@ -13,6 +14,8 @@ from torch.multiprocessing import (
     spawn)  # pyright: ignore[reportPrivateImportUsage]
 from typing_extensions import Concatenate, ParamSpec
 
+from vllm.model_executor.layers.fused_moe.utils import find_free_port
+
 has_deep_ep = importlib.util.find_spec("deep_ep") is not None
 if has_deep_ep:
     from vllm.model_executor.layers.fused_moe.deepep_ht_prepare_finalize import (  # noqa: E501
@@ -92,7 +95,7 @@ def parallel_launch(
             world_size,
             world_size,
             0,
-            "tcp://localhost:29500",
+            f"tcp://{os.getenv('LOCALHOST', 'localhost')}:{find_free_port()}",
             worker,
         ) + args,
         nprocs=world_size,

vllm/model_executor/layers/fused_moe/utils.py

 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+import socket
+from contextlib import closing
 from math import prod
 from typing import Optional
 
@@ -96,3 +98,10 @@ def _fp8_perm(m: torch.Tensor, idx: torch.Tensor) -> torch.Tensor:
         return m.view(dtype=torch.uint8)[idx, ...].view(dtype=m.dtype)
     else:
         return m[idx, ...]
+
+
+def find_free_port():
+    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as s:
+        s.bind(('', 0))
+        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        return s.getsockname()[1]
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