[P/D] NixlConnector DP fixes (#18903)

Signed-off-by: Will Eaton <weaton@redhat.com>

vllm/distributed/kv_transfer/kv_connector/factory.py

@@ -70,7 +70,8 @@ class KVConnectorFactory:
             connector_module = importlib.import_module(connector_module_path)
             connector_cls = getattr(connector_module, connector_name)
         assert issubclass(connector_cls, KVConnectorBase_V1)
-        logger.info("Creating v1 connector with name: %s", connector_name)
+        logger.info("Creating v1 connector with name: %s and engine_id: %s",
+                    connector_name, kv_transfer_config.engine_id)
         # NOTE(Kuntai): v1 connector is explicitly separated into two roles.
         # Scheduler connector:
         # - Co-locate with scheduler process

vllm/distributed/kv_transfer/kv_connector/v1/nixl_connector.py

@@ -19,7 +19,7 @@ from vllm.distributed.kv_transfer.kv_connector.v1.base import (
     KVConnectorBase_V1, KVConnectorMetadata, KVConnectorRole)
 from vllm.distributed.parallel_state import (
     get_tensor_model_parallel_rank, get_tensor_model_parallel_world_size,
-    get_tp_group)
+    get_tp_group, get_world_group)
 from vllm.logger import init_logger
 from vllm.utils import make_zmq_path, make_zmq_socket, round_down
 from vllm.v1.core.sched.output import SchedulerOutput
@@ -334,6 +334,7 @@ class NixlConnectorWorker:
         self.engine_id = engine_id
         self.rank = get_tensor_model_parallel_rank()
         self.world_size = get_tensor_model_parallel_world_size()
+        self.world_rank = get_world_group().rank_in_group
         self.tp_group = get_tp_group()
 
         # KV Caches and nixl tracking data.
@@ -382,7 +383,8 @@ class NixlConnectorWorker:
 
     @staticmethod
     def _nixl_handshake_listener(metadata: NixlAgentMetadata,
-                                 ready_event: threading.Event, rank: int):
+                                 ready_event: threading.Event,
+                                 world_rank: int):
         """Background thread for getting new NIXL handshakes."""
         # NOTE(rob): this is a simple implementation. We will move
         # to a better approach like an ETCD server in the future.
@@ -403,7 +405,7 @@ class NixlConnectorWorker:
         # NOTE(rob): we need each rank to have a unique port. This
         # hack to keeps us moving. We will switch when moving to etcd
         # or where we have a single ZMQ socket in the scheduler.
-        port = envs.VLLM_NIXL_SIDE_CHANNEL_PORT + rank
+        port = envs.VLLM_NIXL_SIDE_CHANNEL_PORT + world_rank
         path = make_zmq_path("tcp", host, port)
         logger.debug("Starting listening on path: %s", path)
         with zmq_ctx(zmq.ROUTER, path) as sock:
@@ -422,7 +424,7 @@ class NixlConnectorWorker:
         # NOTE(rob): we need each rank to have a unique port. This is
         # a hack to keep us moving. We will switch when moving to etcd
         # or where we have a single ZMQ socket in the scheduler.
-        path = make_zmq_path("tcp", host, port + self.rank)
+        path = make_zmq_path("tcp", host, port + self.world_rank)
         logger.debug("Querying metadata on path: %s", path)
         with zmq_ctx(zmq.REQ, path) as sock:
             # Send query for the request.
@@ -529,7 +531,7 @@ class NixlConnectorWorker:
         ready_event = threading.Event()
         self._nixl_handshake_listener_t = threading.Thread(
             target=self._nixl_handshake_listener,
-            args=(metadata, ready_event, self.rank),
+            args=(metadata, ready_event, self.world_rank),
             daemon=True,
             name="nixl_handshake_listener")
         self._nixl_handshake_listener_t.start()

vllm/v1/engine/core.py

@@ -707,6 +707,15 @@ class DPEngineCoreProc(EngineCoreProc):
         assert dp_size > 1
         assert 0 <= local_dp_rank <= dp_rank < dp_size
 
+        if vllm_config.kv_transfer_config is not None:
+            # modify the engine_id and append the local_dp_rank to it to ensure
+            # that the kv_transfer_config is unique for each DP rank.
+            vllm_config.kv_transfer_config.engine_id = (
+                f"{vllm_config.kv_transfer_config.engine_id}_dp{local_dp_rank}"
+            )
+            logger.debug("Setting kv_transfer_config.engine_id to %s",
+                         vllm_config.kv_transfer_config.engine_id)
+
         from vllm.platforms import current_platform
         device_control_env_var = current_platform.device_control_env_var
         world_size = vllm_config.parallel_config.world_size