[BugFix][Nixl][PD] Fix heterogenous TP (#22663)

Signed-off-by: NickLucche <nlucches@redhat.com>
Co-authored-by: Nick Hill <nhill@redhat.com>

Author: NickLucche

vllm/distributed/kv_transfer/kv_connector/factory.py

@@ -4,13 +4,17 @@
 import importlib
 from typing import TYPE_CHECKING, Callable
 
+# yapf: disable
 import vllm.envs as envs
-from vllm.distributed.kv_transfer.kv_connector.base import KVConnectorBase
+from vllm.distributed.kv_transfer.kv_connector.base import (
+    KVConnectorBase, KVConnectorBaseType)
 from vllm.distributed.kv_transfer.kv_connector.v1 import KVConnectorRole
 from vllm.logger import init_logger
 
+# yapf: enable
+
 if TYPE_CHECKING:
-    from vllm.config import VllmConfig
+    from vllm.config import KVTransferConfig, VllmConfig
 
 logger = init_logger(__name__)
 
@@ -42,17 +46,7 @@ def create_connector(
                              f"but found {envs.VLLM_USE_V1=}")
 
         kv_transfer_config = config.kv_transfer_config
-        connector_name = kv_transfer_config.kv_connector
-        if connector_name in cls._registry:
-            connector_cls = cls._registry[connector_name]()
-        else:
-            connector_module_path = kv_transfer_config.kv_connector_module_path
-            if connector_module_path is None:
-                raise ValueError(
-                    f"Unsupported connector type: {connector_name}")
-            connector_module = importlib.import_module(connector_module_path)
-            connector_cls = getattr(connector_module, connector_name)
-        assert issubclass(connector_cls, KVConnectorBase)
+        connector_cls = cls.get_connector_class(kv_transfer_config)
         logger.info("Creating v1 connector with name: %s and engine_id: %s",
                     connector_cls.__name__, kv_transfer_config.engine_id)
         # NOTE(Kuntai): v1 connector is explicitly separated into two roles.
@@ -65,6 +59,23 @@ def create_connector(
         # We build separately to enforce strict separation
         return connector_cls(config, role)
 
+    @classmethod
+    def get_connector_class(
+            cls, kv_transfer_config: "KVTransferConfig"
+    ) -> type[KVConnectorBaseType]:
+        """Get the connector class by name."""
+        connector_name = kv_transfer_config.kv_connector
+        if connector_name in cls._registry:
+            connector_cls = cls._registry[connector_name]()
+        else:
+            connector_module_path = kv_transfer_config.kv_connector_module_path
+            if connector_module_path is None:
+                raise ValueError(
+                    f"Unsupported connector type: {connector_name}")
+            connector_module = importlib.import_module(connector_module_path)
+            connector_cls = getattr(connector_module, connector_name)
+        return connector_cls
+
 
 # Register various connectors here.
 # The registration should not be done in each individual file, as we want to

vllm/distributed/kv_transfer/kv_connector/utils.py

@@ -13,8 +13,8 @@
 import vllm.envs as envs
 from vllm import _custom_ops as ops
 from vllm.config import VllmConfig, get_current_vllm_config
-from vllm.distributed.kv_transfer.kv_connector.v1.base import (
-    KVConnectorBase_V1)
+from vllm.distributed.kv_transfer.kv_connector.factory import (
+    KVConnectorFactory)
 from vllm.logger import init_logger
 from vllm.v1.outputs import KVConnectorOutput, ModelRunnerOutput
 
@@ -106,8 +106,9 @@ def get_kv_connector_cache_layout():
     vllm_config = get_current_vllm_config()
     kv_config = vllm_config.kv_transfer_config
     if kv_config is not None:
-        required_kvcache_layout = (
-            KVConnectorBase_V1.get_required_kvcache_layout(vllm_config))
+        connector_cls = KVConnectorFactory.get_connector_class(kv_config)
+        required_kvcache_layout = connector_cls.get_required_kvcache_layout(
+            vllm_config)
         if required_kvcache_layout is not None:
             return required_kvcache_layout
         logger.info_once("Connectors do not specify a " \
@@ -143,6 +144,8 @@ def update_finished_set(req_ids: Optional[set[str]],
         finished_recving = set[str]()
         for output in outputs:
             output = output.kv_connector_output
+            if not output:
+                continue
             update_finished_set(output.finished_sending,
                                 self._send_remaining_count, finished_sending)
             update_finished_set(output.finished_recving,