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[Frontend] Move warmup into Renderer (#36482)

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Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>
This commit is contained in:
Cyrus Leung
2026-03-09 21:03:21 +08:00
committed by GitHub
parent b0906d8b02
commit 3ec2115015
4 changed files with 60 additions and 158 deletions
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45
vllm/entrypoints/openai/chat_completion/serving.py
View File

@@ -72,6 +72,7 @@ from vllm.logprobs import Logprob
from vllm.outputs import CompletionOutput, RequestOutput
from vllm.parser import ParserManager
from vllm.reasoning import ReasoningParser
from vllm.renderers import ChatParams
from vllm.sampling_params import BeamSearchParams, SamplingParams
from vllm.tokenizers import TokenizerLike
from vllm.tool_parsers import ToolParser
@@ -171,44 +172,14 @@ class OpenAIServingChat(OpenAIServing):
self.supports_code_interpreter = False
self.python_tool = None
async def warmup(self) -> None:
"""
Warm up the chat template processing to avoid first-request latency.
This method triggers Jinja2 template compilation and content format
detection that would otherwise happen on the first real request,
causing increased latency on the first request.
"""
logger.info("Warming up chat template processing...")
start_time = time.perf_counter()
try:
# Create a minimal dummy request
dummy_request = ChatCompletionRequest(
messages=[{"role": "user", "content": "warmup"}],
model=None,
max_completion_tokens=1,
def warmup(self) -> None:
self.renderer.warmup(
ChatParams(
chat_template=self.chat_template,
chat_template_content_format=self.chat_template_content_format,
chat_template_kwargs=self.default_chat_template_kwargs,
)
# Call _preprocess_chat to trigger template compilation
# This forces:
# 1. Chat template content format detection
# 2. Jinja2 template compilation
# 3. Tokenizer initialization for chat
await self._preprocess_chat(
dummy_request,
dummy_request.messages,
default_template=self.chat_template,
default_template_content_format=self.chat_template_content_format,
default_template_kwargs=self.default_chat_template_kwargs,
)
elapsed = (time.perf_counter() - start_time) * 1000
logger.info("Chat template warmup completed in %.1fms", elapsed)
except Exception:
# Log but don't fail server startup if warmup fails
logger.exception("Chat template warmup failed")
)
async def render_chat_request(
self,

3
vllm/entrypoints/openai/generate/api_router.py
View File

@@ -114,9 +114,8 @@ async def init_generate_state(
if "generate" in supported_tasks
else None
)
# Warm up chat template processing to avoid first-request latency
if state.openai_serving_chat is not None:
await state.openai_serving_chat.warmup()
state.openai_serving_chat.warmup()
state.openai_serving_completion = (
OpenAIServingCompletion(
engine_client,

120
vllm/entrypoints/openai/speech_to_text/speech_to_text.py
View File

@@ -42,10 +42,7 @@ from vllm.exceptions import VLLMValidationError
from vllm.inputs import EncoderDecoderInputs, ProcessorInputs
from vllm.logger import init_logger
from vllm.logprobs import FlatLogprobs, Logprob
from vllm.model_executor.models import (
SupportsTranscription,
supports_transcription,
)
from vllm.model_executor.models import SupportsTranscription
from vllm.multimodal.audio import split_audio
from vllm.outputs import RequestOutput
from vllm.renderers.inputs import DictPrompt, EncoderDecoderDictPrompt
@@ -132,121 +129,6 @@ class OpenAISpeechToText(OpenAIServing):
self.default_sampling_params,
)
# Warm up audio preprocessing to avoid first-request latency
self._warmup_audio_preprocessing()
# Warm up input processor with dummy audio
self._warmup_input_processor()
def _warmup_audio_preprocessing(self) -> None:
"""Warm up audio processing libraries to avoid first-request latency.
The first call to librosa functions (load, get_duration, mel-spectrogram)
triggers JIT compilation and library initialization which can take ~7s.
This method warms up these operations during server initialization.
"""
# Skip warmup if librosa is not installed (optional dependency)
if isinstance(librosa, PlaceholderModule):
return
# Skip warmup if model doesn't support transcription
if not supports_transcription(self.model_cls):
return
if getattr(self.model_cls, "skip_warmup_audio_preprocessing", False):
return
try:
warmup_start = time.perf_counter()
logger.info("Warming up audio preprocessing libraries...")
# Create a minimal dummy audio (1 second of silence at target sample rate)
dummy_audio = np.zeros(int(self.asr_config.sample_rate), dtype=np.float32)
# Warm up librosa.load by using librosa functions on the dummy data
# This initializes FFTW, numba JIT, and other audio processing libraries
_ = librosa.get_duration(y=dummy_audio, sr=self.asr_config.sample_rate)
# Warm up mel-spectrogram computation with model-specific parameters
from vllm.transformers_utils.processor import cached_processor_from_config
processor = cached_processor_from_config(self.model_config)
feature_extractor = None
if hasattr(processor, "feature_extractor"):
feature_extractor = processor.feature_extractor
elif hasattr(processor, "audio_processor"):
# For models like GraniteSpeech that use audio_processor
audio_proc = processor.audio_processor
if hasattr(audio_proc, "feature_extractor"):
feature_extractor = audio_proc.feature_extractor
# If audio_processor doesn't have feature_extractor,
# skip mel-spectrogram warmup for these models
if feature_extractor is not None:
_ = librosa.feature.melspectrogram(
y=dummy_audio,
sr=self.asr_config.sample_rate,
n_mels=getattr(feature_extractor, "n_mels", 128),
n_fft=getattr(feature_extractor, "n_fft", 400),
hop_length=getattr(feature_extractor, "hop_length", 160),
)
warmup_elapsed = time.perf_counter() - warmup_start
logger.info("Audio preprocessing warmup completed in %.2fs", warmup_elapsed)
except Exception:
# Don't fail initialization if warmup fails - log exception and continue
logger.exception(
"Audio preprocessing warmup failed (non-fatal): %s. "
"First request may experience higher latency.",
)
def _warmup_input_processor(self) -> None:
"""Warm up input processor with dummy audio to avoid first-request latency.
The first call to renderer.render_cmpl() with multimodal audio
triggers multimodal processing initialization which can take ~2.5s.
This method processes a dummy audio request to warm up the pipeline.
"""
# Skip warmup if model doesn't support transcription
if not supports_transcription(self.model_cls):
return
# Only warm up if model supports transcription methods
if not hasattr(self.model_cls, "get_generation_prompt"):
return
try:
warmup_start = time.perf_counter()
logger.info("Warming up multimodal input processor...")
# Create minimal dummy audio (1 second of silence)
dummy_audio = np.zeros(int(self.asr_config.sample_rate), dtype=np.float32)
# Use the same method that _preprocess_speech_to_text uses
# to create the prompt
dummy_prompt = self.model_cls.get_generation_prompt(
audio=dummy_audio,
stt_config=self.asr_config,
model_config=self.model_config,
language="en",
task_type=self.task_type,
request_prompt="",
to_language=None,
)
parsed_prompt = parse_model_prompt(self.model_config, dummy_prompt)
# Process the dummy input through the input processor
# This will trigger all the multimodal processing initialization
_ = self.renderer.render_cmpl([parsed_prompt])
warmup_elapsed = time.perf_counter() - warmup_start
logger.info("Input processor warmup completed in %.2fs", warmup_elapsed)
except Exception:
# Don't fail initialization if warmup fails - log warning and continue
logger.exception(
"Input processor warmup failed (non-fatal): %s. "
"First request may experience higher latency."
)
@cached_property
def model_cls(self) -> type[SupportsTranscription]:
from vllm.model_executor.model_loader import get_model_cls

50
vllm/renderers/base.py
View File

@@ -158,6 +158,56 @@ class BaseRenderer(ABC, Generic[_T]):
if self._mm_cache_stats is not None:
self._mm_cache_stats.reset = True
def warmup(self, chat_params: ChatParams) -> None:
"""
Warm up this renderer to avoid first-request latency.
For chat requests:
- Jinja2 template compilation
For multi-modal requests:
- Importing libraries such as librosa triggers JIT compilation.
"""
try:
logger.info("Warming up chat template processing...")
start_time = time.perf_counter()
self.render_chat([[{"role": "user", "content": "warmup"}]], chat_params)
elapsed = time.perf_counter() - start_time
logger.info("Chat template warmup completed in %.3fs", elapsed)
except Exception:
logger.exception("Chat template warmup failed")
if self.mm_processor:
from vllm.multimodal.processing import TimingContext
model_config = self.model_config
mm_config = model_config.get_multimodal_config()
processor = self.mm_processor
mm_limits = processor.info.allowed_mm_limits
try:
logger.info("Warming up multi-modal processing...")
start_time = time.perf_counter()
processor_inputs = processor.dummy_inputs.get_dummy_processor_inputs(
seq_len=model_config.max_model_len,
mm_counts=dict.fromkeys(mm_limits, 1),
mm_options=mm_config.limit_per_prompt,
)
_ = processor.apply(
processor_inputs,
timing_ctx=TimingContext(enabled=False),
)
elapsed = time.perf_counter() - start_time
logger.info("Multi-modal warmup completed in %.3fs", elapsed)
except Exception:
logger.exception("Multi-modal warmup failed")
finally:
self.clear_mm_cache()
def shutdown(self) -> None:
mm_processor_cache = self.mm_processor_cache
if mm_processor_cache is not None: