[feature] Enable multi-node inference through Ray backend (#7938)

Signed-off-by: Maciej Bala <mbala@nvidia.com>
Co-authored-by: Bartosz Stefaniak <bstefaniak@nvidia.com>
Co-authored-by: 汪志鹏 <wangzhipeng628@gmail.com>

vllm_omni/diffusion/diffusion_engine.py

@@ -669,8 +669,10 @@ class DiffusionEngine:
                 self._poll_native_kv()
                 worker_execution_completed = True
             except Exception as exc:
+                # Shutdown can interrupt an in-flight executor call. Exit through
+                # the loop tail so pending RPCs are failed instead of left waiting.
                 if self._closed:
-                    return
+                    break
                 worker_execution_completed = False
                 logger.error(
                     "Execution failed for diffusion requests %s", sched_output.scheduled_request_ids, exc_info=True
@@ -1569,6 +1571,10 @@ class DiffusionEngine:
         for stream in pending_streams:
             self._put_queue_output(stream, closed_output)
 
+        # Interrupt remote inference before waiting for the thread blocked on Ray.
+        if self.od_config.distributed_executor_backend == "ray":
+            self.executor.shutdown()
+
         worker_thread = self.worker_thread
         if worker_thread is not None:
             if worker_thread.is_alive():