[Core] Fix abrupt request abort (#18485)

Signed-off-by: nicklucche <nlucches@redhat.com>
Signed-off-by: Nick Hill <nhill@redhat.com>

Co-authored-by: Nick Hill <nhill@redhat.com>

Author: NickLucche

vllm/v1/core/kv_cache_coordinator.py

@@ -164,7 +164,7 @@ def get_blocks(self, request_id: str) -> list[list[KVCacheBlock]]:
         Get the blocks for the request.
         """
         return [
-            manager.req_to_blocks[request_id]
+            manager.req_to_blocks.get(request_id) or []
             for manager in self.single_type_managers
         ]
 

vllm/v1/core/sched/scheduler.py

@@ -76,6 +76,9 @@ def __init__(
         # KV Connector pushes/pull of remote KVs for P/D and offloading.
         self.connector = None
         if self.vllm_config.kv_transfer_config is not None:
+            assert len(self.kv_cache_config.kv_cache_groups) == 1, (
+                "Multiple KV cache groups are not currently supported "
+                "with KV connectors")
             self.connector = KVConnectorFactory.create_connector_v1(
                 config=self.vllm_config, role=KVConnectorRole.SCHEDULER)
 
@@ -985,9 +988,8 @@ def _connector_finished(
         """
         if self.connector is None:
             return False, None
-        assert len(self.kv_cache_config.kv_cache_groups
-                   ) == 1, "KV connector only supports one KV cache group now"
-        block_ids = self.kv_cache_manager.get_block_ids(request.request_id)[0]
+
+        (block_ids, ) = self.kv_cache_manager.get_block_ids(request.request_id)
         return self.connector.request_finished(request, block_ids)
 
     def _update_waiting_for_remote_kv(self, request: Request) -> bool:
@@ -1002,12 +1004,12 @@ def _update_waiting_for_remote_kv(self, request: Request) -> bool:
         and the request state will be moved back to WAITING from
         WAITING_FOR_REMOTE_KV.
         """
+        assert self.connector is not None
         if request.request_id not in self.finished_recving_kv_req_ids:
             return False
-        assert len(self.kv_cache_config.kv_cache_groups
-                   ) == 1, "KV connector only supports one KV cache group now"
+
         # Now that the blocks are ready, actually cache them.
-        block_ids = self.kv_cache_manager.get_block_ids(request.request_id)[0]
+        (block_ids, ) = self.kv_cache_manager.get_block_ids(request.request_id)
         num_computed_tokens = len(block_ids) * self.block_size
         # Handle the case where num request tokens less then one block.
         num_computed_tokens = min(num_computed_tokens, request.num_tokens)