[V1] Eagerly remove finished requests from the batch (#14388)

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

tests/v1/engine/test_engine_core.py

@@ -102,14 +102,24 @@ def test_engine_core(monkeypatch):
         engine_core.add_request(req)
         assert len(engine_core.scheduler.waiting) == 1
         assert len(engine_core.scheduler.running) == 0
+        assert engine_core.scheduler.has_unfinished_requests()
+        assert not engine_core.scheduler.has_finished_requests()
 
         _ = engine_core.step()
         assert len(engine_core.scheduler.waiting) == 0
         assert len(engine_core.scheduler.running) == 1
+        assert engine_core.scheduler.has_unfinished_requests()
+        assert not engine_core.scheduler.has_finished_requests()
 
         engine_core.abort_requests([request_id])
         assert len(engine_core.scheduler.waiting) == 0
         assert len(engine_core.scheduler.running) == 0
+        assert not engine_core.scheduler.has_unfinished_requests()
+        assert engine_core.scheduler.has_finished_requests()
+
+        _ = engine_core.step()
+        assert not engine_core.scheduler.has_unfinished_requests()
+        assert not engine_core.scheduler.has_finished_requests()
 
         # Add, step, abort 1 of the 3.
         req0 = make_request()

tests/v1/engine/test_engine_core_client.py

@@ -50,7 +50,7 @@ def loop_until_done(client: EngineCoreClient, outputs: dict):
         engine_core_outputs = client.get_output().outputs
 
         if len(engine_core_outputs) == 0:
-            break
+            continue
 
         all_finished = True
         for out in engine_core_outputs:
@@ -68,7 +68,7 @@ async def loop_until_done_async(client: EngineCoreClient, outputs: dict):
         engine_core_outputs = (await client.get_output_async()).outputs
 
         if len(engine_core_outputs) == 0:
-            break
+            continue
 
         all_finished = True
         for out in engine_core_outputs:

vllm/v1/core/scheduler.py

@@ -682,6 +682,7 @@ class Scheduler:
         assert RequestStatus.is_finished(finished_status)
         if isinstance(request_ids, str):
             request_ids = (request_ids, )
+        else:
             request_ids = set(request_ids)
 
         for req_id in request_ids:
@@ -714,6 +715,14 @@ class Scheduler:
     def has_unfinished_requests(self) -> bool:
         return self.get_num_unfinished_requests() > 0
 
+    def has_finished_requests(self) -> bool:
+        return len(self.finished_req_ids) > 0
+
+    def has_requests(self):
+        """Returns True if there are unfinished requests, or finished requests
+        not yet returned in SchedulerOutputs."""
+        return self.has_unfinished_requests() or self.has_finished_requests()
+
     def get_num_unscheduled_requests(self) -> int:
         """Number of requests that are not being processed by the executor."""
         return self.get_num_unfinished_requests() - len(self.scheduled_req_ids)

vllm/v1/engine/async_llm.py

@@ -253,13 +253,14 @@ class AsyncLLM(EngineClient):
             while True:
                 # 1) Pull EngineCoreOutputs from the EngineCore.
                 outputs = await self.engine_core.get_output_async()
+                num_outputs = len(outputs.outputs)
 
-                iteration_stats = IterationStats() if self.log_stats else None
+                iteration_stats = IterationStats() if (
+                    self.log_stats and num_outputs) else None
 
                 # Split outputs into chunks of at most
                 # VLLM_V1_OUTPUT_PROC_CHUNK_SIZE, so that we don't block the
                 # event loop for too long.
-                num_outputs = len(outputs.outputs)
                 if num_outputs <= VLLM_V1_OUTPUT_PROC_CHUNK_SIZE:
                     slices = (outputs.outputs, )
                 else:
@@ -313,7 +314,6 @@ class AsyncLLM(EngineClient):
             return
 
         assert scheduler_stats is not None
-        assert iteration_stats is not None
         for stat_logger in self.stat_loggers:
             stat_logger.record(scheduler_stats=scheduler_stats,
                                iteration_stats=iteration_stats)

vllm/v1/engine/core.py

@@ -153,7 +153,9 @@ class EngineCore:
     def step(self) -> EngineCoreOutputs:
         """Schedule, execute, and make output."""
 
-        if not self.scheduler.has_unfinished_requests():
+        # Check for any requests remaining in the scheduler - unfinished,
+        # or finished and not yet removed from the batch.
+        if not self.scheduler.has_requests():
             return EngineCoreOutputs(
                 outputs=[],
                 scheduler_stats=self.scheduler.make_stats(),
@@ -335,7 +337,7 @@ class EngineCoreProc(EngineCore):
         # Loop until process is sent a SIGINT or SIGTERM
         while True:
             # 1) Poll the input queue until there is work to do.
-            while not self.scheduler.has_unfinished_requests():
+            while not self.scheduler.has_requests():
                 logger.debug("EngineCore busy loop waiting.")
                 req = self.input_queue.get()
                 self._handle_client_request(*req)

vllm/v1/metrics/loggers.py

@@ -22,7 +22,7 @@ class StatLoggerBase(ABC):
 
     @abstractmethod
     def record(self, scheduler_stats: SchedulerStats,
-               iteration_stats: IterationStats):
+               iteration_stats: Optional[IterationStats]):
         ...
 
     def log(self):  # noqa
@@ -56,9 +56,10 @@ class LoggingStatLogger(StatLoggerBase):
         return float(np.sum(tracked_stats) / (now - self.last_log_time))
 
     def record(self, scheduler_stats: SchedulerStats,
-               iteration_stats: IterationStats):
+               iteration_stats: Optional[IterationStats]):
         """Log Stats to standard output."""
 
+        if iteration_stats:
             self._track_iteration_stats(iteration_stats)
 
         self.prefix_caching_metrics.observe(scheduler_stats.prefix_cache_stats)
@@ -319,7 +320,7 @@ class PrometheusStatLogger(StatLoggerBase):
         info_gauge.set(1)
 
     def record(self, scheduler_stats: SchedulerStats,
-               iteration_stats: IterationStats):
+               iteration_stats: Optional[IterationStats]):
         """Log to prometheus."""
         self.gauge_scheduler_running.set(scheduler_stats.num_running_reqs)
         self.gauge_scheduler_waiting.set(scheduler_stats.num_waiting_reqs)
@@ -331,6 +332,9 @@ class PrometheusStatLogger(StatLoggerBase):
         self.counter_gpu_prefix_cache_hits.inc(
             scheduler_stats.prefix_cache_stats.hits)
 
+        if iteration_stats is None:
+            return
+
         self.counter_num_preempted_reqs.inc(iteration_stats.num_preempted_reqs)
         self.counter_prompt_tokens.inc(iteration_stats.num_prompt_tokens)
         self.counter_generation_tokens.inc(

vllm/v1/outputs.py

@@ -80,3 +80,13 @@ class ModelRunnerOutput:
     # [prompt_len, num_prompt_logprobs]
     # [prompt_len]
     prompt_logprobs_dict: dict[str, Optional[LogprobsTensors]]
+
+
+EMPTY_MODEL_RUNNER_OUTPUT = ModelRunnerOutput(
+    req_ids=[],
+    req_id_to_index={},
+    sampled_token_ids=[],
+    spec_token_ids=None,
+    logprobs=None,
+    prompt_logprobs_dict={},
+)

vllm/v1/worker/gpu_model_runner.py

@@ -32,7 +32,8 @@ from vllm.v1.core.encoder_cache_manager import compute_encoder_budget
 from vllm.v1.engine.mm_input_cache import MMInputCacheClient
 from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
                                         KVCacheSpec)
-from vllm.v1.outputs import LogprobsTensors, ModelRunnerOutput
+from vllm.v1.outputs import (EMPTY_MODEL_RUNNER_OUTPUT, LogprobsTensors,
+                             ModelRunnerOutput)
 from vllm.v1.sample.metadata import SamplingMetadata
 from vllm.v1.sample.rejection_sampler import INVALID_TOKEN_ID, RejectionSampler
 from vllm.v1.spec_decode.ngram_proposer import NgramProposer
@@ -919,6 +920,9 @@ class GPUModelRunner(LoRAModelRunnerMixin):
         intermediate_tensors: Optional[IntermediateTensors] = None,
     ) -> Union[ModelRunnerOutput, torch.Tensor]:
         self._update_states(scheduler_output)
+        if not scheduler_output.total_num_scheduled_tokens:
+            # Return empty ModelRunnerOuptut if there's no work to do.
+            return EMPTY_MODEL_RUNNER_OUTPUT
 
         if self.is_multimodal_model:
             # Run the multimodal encoder if any.
@@ -1069,7 +1073,7 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             spec_token_ids = self.generate_draft_token_ids(
                 valid_sampled_token_ids)
 
-        model_runner_output = ModelRunnerOutput(
+        return ModelRunnerOutput(
             req_ids=self.input_batch.req_ids,
             req_id_to_index=self.input_batch.req_id_to_index,
             sampled_token_ids=valid_sampled_token_ids,
@@ -1077,7 +1081,6 @@ class GPUModelRunner(LoRAModelRunnerMixin):
             logprobs=logprobs_lists,
             prompt_logprobs_dict=prompt_logprobs_dict,
         )
-        return model_runner_output
 
     def generate_draft_token_ids(
         self,

vllm/v1/worker/tpu_model_runner.py

@@ -29,7 +29,8 @@ from vllm.v1.attention.backends.pallas import (NUM_KV_PAGES_PER_BLOCK,
 from vllm.v1.core.encoder_cache_manager import compute_encoder_budget
 from vllm.v1.kv_cache_interface import (FullAttentionSpec, KVCacheConfig,
                                         KVCacheSpec)
-from vllm.v1.outputs import LogprobsTensors, ModelRunnerOutput
+from vllm.v1.outputs import (EMPTY_MODEL_RUNNER_OUTPUT, LogprobsTensors,
+                             ModelRunnerOutput)
 from vllm.v1.utils import bind_kv_cache
 from vllm.v1.worker.gpu_input_batch import CachedRequestState, InputBatch
 
@@ -546,6 +547,9 @@ class TPUModelRunner:
     ) -> ModelRunnerOutput:
         # Update cached state
         self._update_states(scheduler_output)
+        if not scheduler_output.total_num_scheduled_tokens:
+            # Return empty ModelRunnerOuptut if there's no work to do.
+            return EMPTY_MODEL_RUNNER_OUTPUT
 
         if self.is_multimodal_model:
             # Run the multimodal encoder if any.