[Bugfix] Fix ray instance detect issue (#9439)

vllm/executor/ray_utils.py

@@ -232,6 +232,13 @@ def initialize_ray_cluster(
 
     # Connect to a ray cluster.
     if current_platform.is_rocm() or current_platform.is_xpu():
+        # Try to connect existing ray instance and create a new one if not found
+        try:
+            ray.init("auto")
+        except ConnectionError:
+            logger.warning(
+                "No existing RAY instance detected. "
+                "A new instance will be launched with current node resources.")
             ray.init(address=ray_address,
                      ignore_reinit_error=True,
                      num_gpus=parallel_config.world_size)