[BugFix] Handle unscheduled requests properly when async scheduling (#27756)

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

tests/v1/tpu/worker/test_tpu_model_runner.py

@@ -212,10 +212,12 @@ def test_update_states_request_resumed(model_runner):
     # resume req
     cached_req_data = CachedRequestData(
         req_ids=[req_id],
-        resumed_from_preemption=[False],
+        resumed_req_ids={req_id},
         new_token_ids=[[]],
+        all_token_ids={req_id: scheduler_output.scheduled_new_reqs[0].prompt_token_ids},
         new_block_ids=[([],)],
         num_computed_tokens=[0],
+        num_output_tokens=[0],
     )
 
     scheduler_output = SchedulerOutput(

tests/v1/worker/test_gpu_model_runner.py

@@ -259,10 +259,10 @@ def test_update_states_request_resumed(model_runner, dist_init):
     # resume req
     cached_req_data = CachedRequestData(
         req_ids=[req_id],
-        resumed_from_preemption=[False],
+        resumed_req_ids=set(),
         new_token_ids=[[]],
-        resumed_req_token_ids=[None],
-        new_block_ids=([[0]],),
+        all_token_ids={},
+        new_block_ids=[([0],)],
         num_computed_tokens=[0],
         num_output_tokens=[0],
     )

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

@@ -494,5 +494,5 @@ def yield_req_data(
     yield from zip(
         cached_reqs.req_ids,
         cached_reqs.new_block_ids,
-        cached_reqs.resumed_from_preemption,
+        (req_id in cached_reqs.resumed_req_ids for req_id in cached_reqs.req_ids),
     )

vllm/distributed/kv_transfer/kv_connector/v1/p2p/p2p_nccl_connector.py

@@ -415,10 +415,10 @@ class P2pNcclConnector(KVConnectorBase_V1):
         for i, req_id in enumerate(cached_reqs.req_ids):
             num_computed_tokens = cached_reqs.num_computed_tokens[i]
             new_block_ids = cached_reqs.new_block_ids[i]
-            resumed_from_preemption = cached_reqs.resumed_from_preemption[i]
+            resumed_from_preemption = req_id in cached_reqs.resumed_req_ids
 
             if self.is_producer:
-                num_scheduled_tokens = (scheduler_output.num_scheduled_tokens)[req_id]
+                num_scheduled_tokens = scheduler_output.num_scheduled_tokens[req_id]
                 num_tokens = num_scheduled_tokens + num_computed_tokens
                 assert req_id in self.chunked_prefill
                 assert new_block_ids is not None

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

@@ -336,7 +336,7 @@ class SharedStorageConnector(KVConnectorBase_V1):
 
         cached_reqs = scheduler_output.scheduled_cached_reqs
         for i, req_id in enumerate(cached_reqs.req_ids):
-            resumed_from_preemption = cached_reqs.resumed_from_preemption[i]
+            resumed_from_preemption = req_id in cached_reqs.resumed_req_ids
             if not resumed_from_preemption or req_id not in self._requests_need_load:
                 continue
 

vllm/v1/core/sched/output.py

@@ -2,8 +2,11 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 from dataclasses import dataclass
+from functools import cached_property
 from typing import TYPE_CHECKING
 
+from typing_extensions import deprecated
+
 from vllm._bc_linter import bc_linter_include
 
 if TYPE_CHECKING:
@@ -96,16 +99,16 @@ class NewRequestData:
 @dataclass
 class CachedRequestData:
     req_ids: list[str]
-    # If resumed_from_preemption is False, new_block_ids will be appended to
-    # the request's block IDs. If True, new_block_ids will be used as the
+    # For request ids not in resumed_req_ids, new_block_ids will be appended to
+    # the request's block IDs. For those in the set, new_block_ids will be used as the
     # request's block IDs instead of appending to the existing block IDs.
-    resumed_from_preemption: list[bool]
+    resumed_req_ids: set[str]
     # NOTE(woosuk): new_token_ids is only used for pipeline parallelism.
     # When PP is not used, new_token_ids will be empty.
     new_token_ids: list[list[int]]
-    # If resumed_from_preemption is True, propogate the token ids to the
-    # connector, otherwise will be empty.
-    resumed_req_token_ids: list[list[int] | None]
+    # For requests not scheduled in the last step, propagate the token ids to the
+    # connector. Won't contain requests that were scheduled in the prior step.
+    all_token_ids: dict[str, list[int]]
     new_block_ids: list[tuple[list[int], ...] | None]
     num_computed_tokens: list[int]
     num_output_tokens: list[int]
@@ -114,13 +117,26 @@ class CachedRequestData:
     def num_reqs(self) -> int:
         return len(self.req_ids)
 
+    @cached_property
+    @deprecated("use resumed_req_ids field")
+    def resumed_from_preemption(self) -> list[bool]:
+        return [req_id in self.resumed_req_ids for req_id in self.req_ids]
+
+    @cached_property
+    @deprecated("use all_token_ids field")
+    def resumed_req_token_ids(self) -> list[list[int] | None]:
+        return [
+            self.all_token_ids[req_id] if req_id in self.resumed_req_ids else None
+            for req_id in self.req_ids
+        ]
+
     @classmethod
     def make_empty(cls) -> "CachedRequestData":
         return cls(
             req_ids=[],
-            resumed_from_preemption=[],
+            resumed_req_ids=set(),
             new_token_ids=[],
-            resumed_req_token_ids=[],
+            all_token_ids={},
             new_block_ids=[],
             num_computed_tokens=[],
             num_output_tokens=[],

vllm/v1/core/sched/scheduler.py

@@ -71,6 +71,7 @@ class Scheduler(SchedulerInterface):
         self.finished_req_ids_dict: dict[int, set[str]] | None = (
             defaultdict(set) if include_finished_set else None
         )
+        self.prev_step_scheduled_req_ids: set[str] = set()
 
         # Scheduling constraints.
         self.max_num_running_reqs = self.scheduler_config.max_num_seqs
@@ -444,14 +445,9 @@ class Scheduler(SchedulerInterface):
                     # `request.num_prompt_tokens` to consider the resumed
                     # requests, which have output tokens.
                     num_new_tokens = request.num_tokens - num_computed_tokens
-                    if (
-                        0
-                        < self.scheduler_config.long_prefill_token_threshold
-                        < num_new_tokens
-                    ):
-                        num_new_tokens = (
-                            self.scheduler_config.long_prefill_token_threshold
-                        )
+                    threshold = self.scheduler_config.long_prefill_token_threshold
+                    if 0 < threshold < num_new_tokens:
+                        num_new_tokens = threshold
 
                     # chunked prefill has to be enabled explicitly to allow
                     # pooling requests to be chunked
@@ -620,6 +616,11 @@ class Scheduler(SchedulerInterface):
         structured_output_request_ids, grammar_bitmask = self.get_grammar_bitmask(
             num_scheduled_tokens.keys(), scheduled_spec_decode_tokens
         )
+
+        # Record the request ids that were scheduled in this step.
+        self.prev_step_scheduled_req_ids.clear()
+        self.prev_step_scheduled_req_ids.update(num_scheduled_tokens.keys())
+
         scheduler_output = SchedulerOutput(
             scheduled_new_reqs=new_reqs_data,
             scheduled_cached_reqs=cached_reqs_data,
@@ -691,14 +692,12 @@ class Scheduler(SchedulerInterface):
         req_ids: list[str] = []
         new_token_ids: list[list[int]] = []
         new_block_ids: list[tuple[list[int], ...] | None] = []
-        resumed_req_token_ids: list[list[int] | None] = []
+        all_token_ids: dict[str, list[int]] = {}
         num_computed_tokens: list[int] = []
         num_output_tokens: list[int] = []
+        resumed_req_ids = set()
 
-        # Because resumed_reqs is usually empty, it is more efficient to do
-        # in-place appending so that we don't need to allocate a new list.
-        resumed_from_preemption = [False] * len(running_reqs)
-        resumed_from_preemption += [True] * len(resumed_reqs)
+        num_running_reqs = len(running_reqs)
         for idx, req in enumerate(itertools.chain(running_reqs, resumed_reqs)):
             req_id = req.request_id
             req_ids.append(req_id)
@@ -715,12 +714,14 @@ class Scheduler(SchedulerInterface):
                     req.num_computed_tokens : req.num_computed_tokens + num_tokens
                 ]
                 new_token_ids.append(token_ids)
-            resumed_token_ids = None
-            if resumed_from_preemption[idx]:
-                resumed_token_ids = req.all_token_ids[
+            scheduled_in_prev_step = req_id in self.prev_step_scheduled_req_ids
+            if idx >= num_running_reqs:
+                assert not scheduled_in_prev_step
+                resumed_req_ids.add(req_id)
+            if not scheduled_in_prev_step:
+                all_token_ids[req_id] = req.all_token_ids[
                     : req.num_computed_tokens + num_tokens
                 ]
-            resumed_req_token_ids.append(resumed_token_ids)
             new_block_ids.append(
                 req_to_new_blocks[req_id].get_block_ids(allow_none=True)
             )
@@ -731,9 +732,9 @@ class Scheduler(SchedulerInterface):
 
         return CachedRequestData(
             req_ids=req_ids,
-            resumed_from_preemption=resumed_from_preemption,
+            resumed_req_ids=resumed_req_ids,
             new_token_ids=new_token_ids,
-            resumed_req_token_ids=resumed_req_token_ids,
+            all_token_ids=all_token_ids,
             new_block_ids=new_block_ids,
             num_computed_tokens=num_computed_tokens,
             num_output_tokens=num_output_tokens,

vllm/v1/worker/gpu_model_runner.py

@@ -706,7 +706,7 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             req_state = self.requests[req_id]
             num_computed_tokens = req_data.num_computed_tokens[i]
             new_block_ids = req_data.new_block_ids[i]
-            resumed_from_preemption = req_data.resumed_from_preemption[i]
+            resumed_from_preemption = req_id in req_data.resumed_req_ids
             num_output_tokens = req_data.num_output_tokens[i]
 
             # Update the cached states.
@@ -754,16 +754,17 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
                 # Replace the existing block IDs with the new ones.
                 req_state.block_ids = new_block_ids
 
-                if self.use_async_scheduling and num_output_tokens > 0:
-                    # We must recover the output token ids for resumed requests in the
-                    # async scheduling case, so that correct input_ids are obtained.
-                    resumed_token_ids = req_data.resumed_req_token_ids[i]
-                    assert resumed_token_ids is not None
-                    req_state.output_token_ids = resumed_token_ids[-num_output_tokens:]
             if req_index is None:
                 # The request is not in the persistent batch.
                 # The request was either preempted and resumed later, or was not
                 # scheduled in the previous step and needs to be added again.
+
+                if self.use_async_scheduling and num_output_tokens > 0:
+                    # We must recover the output token ids for resumed requests in the
+                    # async scheduling case, so that correct input_ids are obtained.
+                    resumed_token_ids = req_data.all_token_ids[req_id]
+                    req_state.output_token_ids = resumed_token_ids[-num_output_tokens:]
+
                 reqs_to_add.append(req_state)
                 continue
 

vllm/v1/worker/tpu_model_runner.py

@@ -483,7 +483,7 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             req_state = self.requests[req_id]
             num_computed_tokens = req_data.num_computed_tokens[i]
             new_block_ids = req_data.new_block_ids[i]
-            resumed_from_preemption = req_data.resumed_from_preemption[i]
+            resumed_from_preemption = req_id in req_data.resumed_req_ids
 
             # Update the cached states.
             req_state.num_computed_tokens = num_computed_tokens