[WIP]dynamic port to solve port confict

tests/v1/distributed/test_external_lb_dp.py

@@ -2,6 +2,7 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 import asyncio
 import os
+import socket
 import threading
 import time
 from contextlib import AsyncExitStack
@@ -20,6 +21,29 @@
 DP_SIZE = int(os.getenv("DP_SIZE", "2"))
 # Default tensor parallel size to use
 TP_SIZE = int(os.getenv("TP_SIZE", "1"))
+# Make sure CCL worker count is set for data parallelism
+os.environ["CCL_WORKER_COUNT"] = str(DP_SIZE)
+
+
+def is_port_available(port: int, host: str = "127.0.0.1") -> bool:
+    # Try to bind to the port to check if it's available. This is more reliable
+    # than trying to connect.
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+        try:
+            s.bind((host, port))
+            return True
+        except OSError:
+            return False
+
+
+def get_unique_port(start_port=8000):
+    """Find an available port"""
+    port = start_port
+    while not is_port_available(port):
+        port += 1  # Increment until an available port is found
+        if port > start_port + 100:  # Limit the search range
+            raise RuntimeError("No available ports")
+    return port
 
 
 class ExternalLBServerManager:
@@ -44,6 +68,14 @@ def __init__(
 
     def __enter__(self) -> list[tuple[RemoteOpenAIServer, list[str]]]:
         """Start all server instances for external LB mode."""
+
+        allocated_ports = []
+        last_port = 7999
+        for _ in range(self.dp_size):
+            port = get_unique_port(start_port=last_port + 1)
+            allocated_ports.append(port)
+            last_port = port
+
         for rank in range(self.dp_size):
             # Create server args for this specific rank
             server_args = self.base_server_args.copy()
@@ -60,7 +92,7 @@ def __enter__(self) -> list[tuple[RemoteOpenAIServer, list[str]]]:
                     "--tensor-parallel-size",
                     str(self.tp_size),
                     "--port",
-                    str(8000 + rank),  # Different port for each rank
+                    str(allocated_ports[rank]),  # Different port for each rank
                     "--api-server-count",
                     str(self.api_server_count),
                 ]