Files
LocalAI/backend/python/vllm/backend.py
pos-ei-don b4c0dc67fe feat(vllm): progressive streaming via parser.extract_tool_calls_streaming (follow-up to #10346) (#10351)
* fix(vllm): don't stream raw tool-call markup as content when a tool parser is active

When a tool_parser is configured and the request carries tools, the streaming
loop emitted every text delta as delta.content — including the model's raw
tool-call markup (e.g. <tool_call>...) — because extract_tool_calls only runs
on the full output after the stream. Clients streaming a tool call therefore
saw the unparsed tool-call syntax as assistant content.

Buffer the text while a tool parser is active for the request; the existing
end-of-stream chat_delta already carries the parsed tool_calls (or the cleaned
content), which the Go side converts to SSE deltas. Non-tool-parser streaming
is unchanged.

Add a server-less regression test covering both the tool-call case (no raw
markup leaked as content) and the plain-text case (content delivered exactly
once — guards against double-emitting the buffered content).

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>

* test(vllm): add expectedFailure test for progressive streaming with tool parser (Case 3, #582)

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>

* test(vllm): add Cases 4+5 — marker split across chunks + false-positive prefix (TDD, Option B state machine, #582)

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>

* feat(vllm): progressive streaming via parser.extract_tool_calls_streaming

When a tool parser is active for a tool-enabled streaming request,
#10346 buffers the entire generation and surfaces it on the final
chunk to prevent raw tool-call markup from leaking as delta.content.
This is correct but turns the request into effectively non-streaming
for plain-text responses — the client sees nothing until the model
stops.

Every concrete tool parser shipped with vLLM 0.23+ already implements
extract_tool_calls_streaming (Granite4, Qwen3Coder, DeepSeekV31, Jamba,
Ernie45, Hermes2Pro, llama3_json, mistral, …). Use it: instantiate
the parser before the streaming loop and call its streaming method per
delta, emitting DeltaMessage(content=…) or DeltaMessage(tool_calls=[…])
when the parser is ready.

Falls back to the existing #10346 buffer path when:
  - the parser does not have extract_tool_calls_streaming, OR
  - extract_tool_calls_streaming raises mid-stream (logged, the
    rest of the request finishes via post-loop extract_tool_calls).

Tests (TestStreamingToolParser):
  1. Buffer path: no markup leaked, no content duplication
  2. Native streaming: plain-text response streams progressively
  3. Native streaming: tool_call structured, no markup leaked
  4. Native streaming exception → graceful fallback, no markup, no crash
  5. No tool parser → unchanged per-delta content stream

E2E verified against qwen3_coder on vLLM 0.23.0 (NVIDIA GB10 / arm64 / CUDA 13).

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>

* docs(vllm): add server-side TTFT benchmark for the streaming tool-parser path

Self-contained stdlib-only script that measures time-to-first-token (TTFT)
for the vLLM backend's two streaming scenarios:

  - tool_call:  request mentions a tool; model is expected to call it
  - plain_text: request offers a tool but explicitly asks for prose

Use this to compare:
  - the buffer-all path (#10346)         → plain_text TTFT ≈ total response time
  - the native-streaming path (this PR)  → plain_text TTFT ≈ true first-token time

  python examples/vllm-bench/ttft_streaming_tool_parser.py \\
      --url http://localhost:8080 --model my-coder --runs 3

Lives under examples/ so it does not interfere with the test suite.

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>

* examples/vllm-bench: add long-text scenario (8 paragraphs, 1500 tokens)

The long-text scenario shows the buffering vs streaming difference most
dramatically: with the buffer-all path, the client receives nothing for
20+ seconds and then the entire 1500-token response at once. With native
streaming, the first token arrives in tens of milliseconds and the
response flows progressively.

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>

---------

Signed-off-by: pos-ei-don <1822533+pos-ei-don@users.noreply.github.com>
Co-authored-by: Philipp Wacker <philipp.wacker@ibf-solutions.com>
2026-06-21 17:07:15 +02:00

926 lines
39 KiB
Python

#!/usr/bin/env python3
import asyncio
import dataclasses
import difflib
from concurrent import futures
import argparse
import signal
import sys
import os
import json
import time
import gc
import tempfile
from typing import List
from PIL import Image
import backend_pb2
import backend_pb2_grpc
import grpc
sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'common'))
sys.path.insert(0, os.path.join(os.path.dirname(__file__), 'common'))
from grpc_auth import get_auth_interceptors
from vllm.engine.arg_utils import AsyncEngineArgs
from vllm.engine.async_llm_engine import AsyncLLMEngine
from vllm.sampling_params import SamplingParams
from vllm.utils import random_uuid
try:
from vllm.tokenizers import get_tokenizer # vLLM >= 0.22
except ImportError:
from vllm.transformers_utils.tokenizer import get_tokenizer # vLLM < 0.22
from vllm.multimodal.utils import fetch_image
from vllm.assets.video import VideoAsset
import base64
import io
# Version-compat imports — wrap in try/except for older vLLM versions
try:
from vllm.tool_parsers import ToolParserManager
HAS_TOOL_PARSERS = True
except ImportError:
HAS_TOOL_PARSERS = False
try:
from vllm.reasoning import ReasoningParserManager
HAS_REASONING_PARSERS = True
except ImportError:
HAS_REASONING_PARSERS = False
# vLLM >= 0.23 renamed GuidedDecodingParams -> StructuredOutputsParams and the
# SamplingParams field guided_decoding -> structured_outputs.
try:
from vllm.sampling_params import StructuredOutputsParams
HAS_GUIDED_DECODING = True
except ImportError:
HAS_GUIDED_DECODING = False
_ONE_DAY_IN_SECONDS = 60 * 60 * 24
# If MAX_WORKERS are specified in the environment use it, otherwise default to 1
MAX_WORKERS = int(os.environ.get('PYTHON_GRPC_MAX_WORKERS', '1'))
# Implement the BackendServicer class with the service methods
class BackendServicer(backend_pb2_grpc.BackendServicer):
"""
A gRPC servicer that implements the Backend service defined in backend.proto.
"""
def generate(self,prompt, max_new_tokens):
"""
Generates text based on the given prompt and maximum number of new tokens.
Args:
prompt (str): The prompt to generate text from.
max_new_tokens (int): The maximum number of new tokens to generate.
Returns:
str: The generated text.
"""
self.generator.end_beam_search()
# Tokenizing the input
ids = self.generator.tokenizer.encode(prompt)
self.generator.gen_begin_reuse(ids)
initial_len = self.generator.sequence[0].shape[0]
has_leading_space = False
decoded_text = ''
for i in range(max_new_tokens):
token = self.generator.gen_single_token()
if i == 0 and self.generator.tokenizer.tokenizer.IdToPiece(int(token)).startswith(''):
has_leading_space = True
decoded_text = self.generator.tokenizer.decode(self.generator.sequence[0][initial_len:])
if has_leading_space:
decoded_text = ' ' + decoded_text
if token.item() == self.generator.tokenizer.eos_token_id:
break
return decoded_text
def _parse_options(self, options_list):
"""Parse Options[] key:value string list into a dict."""
opts = {}
for opt in options_list:
if ":" not in opt:
continue
key, value = opt.split(":", 1)
opts[key.strip()] = value.strip()
return opts
def _apply_engine_args(self, engine_args, engine_args_json):
"""Apply user-supplied engine_args (JSON object) onto an AsyncEngineArgs.
Returns a new AsyncEngineArgs with the typed fields preserved and the
user's overrides layered on top. Uses ``dataclasses.replace`` so vLLM's
``__post_init__`` re-runs and auto-converts dict-valued fields like
``compilation_config`` / ``attention_config`` into their dataclass form.
``speculative_config`` and ``kv_transfer_config`` are accepted as dicts
directly (vLLM converts them at engine init).
Unknown keys raise ValueError with the closest valid field as a hint.
"""
if not engine_args_json:
return engine_args
try:
extra = json.loads(engine_args_json)
except json.JSONDecodeError as e:
raise ValueError(f"engine_args is not valid JSON: {e}") from e
if not isinstance(extra, dict):
raise ValueError(
f"engine_args must be a JSON object, got {type(extra).__name__}"
)
valid = {f.name for f in dataclasses.fields(type(engine_args))}
for key in extra:
if key not in valid:
suggestion = difflib.get_close_matches(key, valid, n=1)
hint = f" did you mean {suggestion[0]!r}?" if suggestion else ""
raise ValueError(f"unknown engine_args key {key!r}.{hint}")
return dataclasses.replace(engine_args, **extra)
def _messages_to_dicts(self, messages):
"""Convert proto Messages to list of dicts suitable for apply_chat_template()."""
result = []
for msg in messages:
d = {"role": msg.role, "content": msg.content or ""}
if msg.name:
d["name"] = msg.name
if msg.tool_call_id:
d["tool_call_id"] = msg.tool_call_id
if msg.reasoning_content:
d["reasoning_content"] = msg.reasoning_content
if msg.tool_calls:
try:
tool_calls = json.loads(msg.tool_calls)
except json.JSONDecodeError:
pass
else:
# OpenAI wire format carries function.arguments as a
# JSON-encoded string, but chat templates (e.g. Qwen3)
# iterate over it as a mapping. vLLM's own OpenAI server
# parses arguments before applying the template, so do
# the same here.
if isinstance(tool_calls, list):
for tc in tool_calls:
func = tc.get("function") if isinstance(tc, dict) else None
if isinstance(func, dict) and isinstance(func.get("arguments"), str):
try:
func["arguments"] = json.loads(func["arguments"])
except json.JSONDecodeError:
pass
d["tool_calls"] = tool_calls
result.append(d)
return result
def Health(self, request, context):
"""
Returns a health check message.
Args:
request: The health check request.
context: The gRPC context.
Returns:
backend_pb2.Reply: The health check reply.
"""
return backend_pb2.Reply(message=bytes("OK", 'utf-8'))
async def LoadModel(self, request, context):
"""
Loads a language model.
Args:
request: The load model request.
context: The gRPC context.
Returns:
backend_pb2.Result: The load model result.
"""
engine_args = AsyncEngineArgs(
model=request.Model,
)
if request.Quantization != "":
engine_args.quantization = request.Quantization
if request.LoadFormat != "":
engine_args.load_format = request.LoadFormat
if request.GPUMemoryUtilization != 0:
engine_args.gpu_memory_utilization = request.GPUMemoryUtilization
if request.TrustRemoteCode:
engine_args.trust_remote_code = request.TrustRemoteCode
if request.EnforceEager:
engine_args.enforce_eager = request.EnforceEager
if request.TensorParallelSize:
engine_args.tensor_parallel_size = request.TensorParallelSize
if request.SwapSpace != 0:
engine_args.swap_space = request.SwapSpace
if request.MaxModelLen != 0:
engine_args.max_model_len = request.MaxModelLen
if request.DisableLogStatus:
engine_args.disable_log_status = request.DisableLogStatus
if request.DType != "":
engine_args.dtype = request.DType
if request.LimitImagePerPrompt != 0 or request.LimitVideoPerPrompt != 0 or request.LimitAudioPerPrompt != 0:
# limit-mm-per-prompt defaults to 1 per modality, based on vLLM docs
engine_args.limit_mm_per_prompt = {
"image": max(request.LimitImagePerPrompt, 1),
"video": max(request.LimitVideoPerPrompt, 1),
"audio": max(request.LimitAudioPerPrompt, 1)
}
# engine_args from YAML overrides typed fields above so operators can
# tune anything the AsyncEngineArgs dataclass exposes without waiting
# on protobuf changes.
try:
engine_args = self._apply_engine_args(engine_args, request.EngineArgs)
except ValueError as err:
print(f"engine_args error: {err}", file=sys.stderr)
return backend_pb2.Result(success=False, message=str(err))
try:
self.llm = AsyncLLMEngine.from_engine_args(engine_args)
except Exception as err:
print(f"Unexpected {err=}, {type(err)=}", file=sys.stderr)
return backend_pb2.Result(success=False, message=f"Unexpected {err=}, {type(err)=}")
try:
# vLLM >= 0.14 removed get_model_config() on AsyncLLM; the tokenizer
# is either already loaded on the engine or can be built from the
# Model name directly.
tokenizer = None
if hasattr(self.llm, "get_tokenizer"):
try:
tokenizer = await self.llm.get_tokenizer()
except TypeError:
tokenizer = self.llm.get_tokenizer()
except Exception:
tokenizer = None
if tokenizer is None and hasattr(self.llm, "tokenizer"):
tokenizer = self.llm.tokenizer
if tokenizer is None:
tokenizer = get_tokenizer(
request.Model,
trust_remote_code=bool(request.TrustRemoteCode),
truncation_side="left",
)
self.tokenizer = tokenizer
except Exception as err:
return backend_pb2.Result(success=False, message=f"Unexpected {err=}, {type(err)=}")
# Parse options for parser selection
opts = self._parse_options(request.Options)
# Instantiate tool/reasoning parser classes (they'll be instantiated per-request with tokenizer)
self.tool_parser_cls = None
self.reasoning_parser_cls = None
if HAS_TOOL_PARSERS and opts.get("tool_parser"):
try:
self.tool_parser_cls = ToolParserManager.get_tool_parser(opts["tool_parser"])
print(f"Loaded tool_parser: {opts['tool_parser']}", file=sys.stderr)
except Exception as e:
print(f"Failed to load tool_parser {opts.get('tool_parser')}: {e}", file=sys.stderr)
if HAS_REASONING_PARSERS and opts.get("reasoning_parser"):
try:
self.reasoning_parser_cls = ReasoningParserManager.get_reasoning_parser(opts["reasoning_parser"])
print(f"Loaded reasoning_parser: {opts['reasoning_parser']}", file=sys.stderr)
except Exception as e:
print(f"Failed to load reasoning_parser {opts.get('reasoning_parser')}: {e}", file=sys.stderr)
print("Model loaded successfully", file=sys.stderr)
return backend_pb2.Result(message="Model loaded successfully", success=True)
async def Predict(self, request, context):
"""
Generates text based on the given prompt and sampling parameters.
Args:
request: The predict request.
context: The gRPC context.
Returns:
backend_pb2.Reply: The predict result.
"""
gen = self._predict(request, context, streaming=False)
res = await gen.__anext__()
return res
def Embedding(self, request, context):
"""
A gRPC method that calculates embeddings for a given sentence.
Args:
request: An EmbeddingRequest object that contains the request parameters.
context: A grpc.ServicerContext object that provides information about the RPC.
Returns:
An EmbeddingResult object that contains the calculated embeddings.
"""
print("Calculated embeddings for: " + request.Embeddings, file=sys.stderr)
outputs = self.model.encode(request.Embeddings)
# Check if we have one result at least
if len(outputs) == 0:
context.set_code(grpc.StatusCode.INVALID_ARGUMENT)
context.set_details("No embeddings were calculated.")
return backend_pb2.EmbeddingResult()
return backend_pb2.EmbeddingResult(embeddings=outputs[0].outputs.embedding)
async def PredictStream(self, request, context):
"""
Generates text based on the given prompt and sampling parameters, and streams the results.
Args:
request: The predict stream request.
context: The gRPC context.
Returns:
backend_pb2.Result: The predict stream result.
"""
iterations = self._predict(request, context, streaming=True)
try:
async for iteration in iterations:
yield iteration
finally:
await iterations.aclose()
async def TokenizeString(self, request, context):
if not hasattr(self, 'tokenizer') or self.tokenizer is None:
context.set_code(grpc.StatusCode.FAILED_PRECONDITION)
context.set_details("Model/tokenizer not loaded")
return backend_pb2.TokenizationResponse()
try:
tokens = self.tokenizer.encode(request.Prompt)
return backend_pb2.TokenizationResponse(length=len(tokens), tokens=tokens)
except Exception as e:
context.set_code(grpc.StatusCode.INTERNAL)
context.set_details(str(e))
return backend_pb2.TokenizationResponse()
async def Free(self, request, context):
try:
if hasattr(self, 'llm'):
del self.llm
if hasattr(self, 'tokenizer'):
del self.tokenizer
self.tool_parser_cls = None
self.reasoning_parser_cls = None
gc.collect()
try:
import torch
if torch.cuda.is_available():
torch.cuda.empty_cache()
except ImportError:
pass
return backend_pb2.Result(success=True, message="Model freed")
except Exception as e:
return backend_pb2.Result(success=False, message=str(e))
async def Score(self, request, context):
"""
Joint log-probability of each candidate continuation given the
shared prompt. Used by routing-policy multi-label classification
(read the distribution rather than asking the model to emit a
single argmax label), reranking, and reward-model scoring.
Implementation uses vLLM's `prompt_logprobs` to recover the
per-token log P(token_i | tokens_<i) for the full concatenated
sequence; the candidate's tokens are the suffix whose logprobs
get summed. max_tokens=1 because vLLM requires at least one
generated token; the generated token is discarded.
"""
if not hasattr(self, 'llm') or self.llm is None:
context.set_code(grpc.StatusCode.FAILED_PRECONDITION)
context.set_details("Model not loaded")
return backend_pb2.ScoreResponse()
if not hasattr(self, 'tokenizer') or self.tokenizer is None:
context.set_code(grpc.StatusCode.FAILED_PRECONDITION)
context.set_details("Tokenizer not available")
return backend_pb2.ScoreResponse()
if len(request.candidates) == 0:
context.set_code(grpc.StatusCode.INVALID_ARGUMENT)
context.set_details("candidates must be non-empty")
return backend_pb2.ScoreResponse()
try:
prompt = request.prompt or ""
prompt_token_ids = self.tokenizer.encode(prompt)
prompt_len = len(prompt_token_ids)
results = []
for candidate in request.candidates:
# Tokenise the concatenated sequence. We can't naively
# use len(prompt_tokens) + len(tokenizer.encode(candidate))
# because BPE merges at the boundary may produce a
# different tokenisation. Encoding the joined text and
# walking the divergence point is the correct primitive.
full_text = prompt + candidate
full_token_ids = self.tokenizer.encode(full_text)
divergence = prompt_len
min_len = min(prompt_len, len(full_token_ids))
for i in range(min_len):
if prompt_token_ids[i] != full_token_ids[i]:
divergence = i
break
candidate_token_ids = full_token_ids[divergence:]
num_candidate_tokens = len(candidate_token_ids)
if num_candidate_tokens == 0:
results.append(backend_pb2.CandidateScore(
log_prob=0.0,
length_normalized_log_prob=0.0,
num_tokens=0,
))
continue
sampling = SamplingParams(
max_tokens=1,
temperature=0.0,
prompt_logprobs=1,
detokenize=False,
)
request_id = random_uuid()
last_output = None
outputs_iter = self.llm.generate(
{"prompt": full_text},
sampling_params=sampling,
request_id=request_id,
)
try:
async for out in outputs_iter:
last_output = out
finally:
try:
await outputs_iter.aclose()
except Exception:
pass
if last_output is None or not getattr(last_output, "prompt_logprobs", None):
context.set_code(grpc.StatusCode.INTERNAL)
context.set_details("vLLM did not return prompt_logprobs")
return backend_pb2.ScoreResponse()
prompt_logprobs = last_output.prompt_logprobs
total = 0.0
tokens_proto = []
for offset, tok_id in enumerate(candidate_token_ids):
position = divergence + offset
if position >= len(prompt_logprobs) or prompt_logprobs[position] is None:
continue
entry = prompt_logprobs[position]
lp_obj = entry.get(tok_id)
if lp_obj is not None:
lp = lp_obj.logprob
else:
# Token not in top-K; vLLM's top-1 may miss it.
# Fall back to the lowest available logprob in the
# entry — a conservative lower-bound on the true
# log P, biased against this candidate.
lp = min(v.logprob for v in entry.values())
total += lp
if request.include_token_logprobs:
tokens_proto.append(backend_pb2.TokenLogProb(
token=self.tokenizer.decode([tok_id]),
log_prob=lp,
))
cs = backend_pb2.CandidateScore(
log_prob=total,
num_tokens=num_candidate_tokens,
)
if request.length_normalize and num_candidate_tokens > 0:
cs.length_normalized_log_prob = total / num_candidate_tokens
if tokens_proto:
cs.tokens.extend(tokens_proto)
results.append(cs)
return backend_pb2.ScoreResponse(candidates=results)
except Exception as e:
print(f"Score error: {e}", file=sys.stderr)
context.set_code(grpc.StatusCode.INTERNAL)
context.set_details(str(e))
return backend_pb2.ScoreResponse()
async def _predict(self, request, context, streaming=False):
# Build the sampling parameters
# NOTE: this must stay in sync with the vllm backend
request_to_sampling_params = {
"N": "n",
"PresencePenalty": "presence_penalty",
"FrequencyPenalty": "frequency_penalty",
"RepetitionPenalty": "repetition_penalty",
"Temperature": "temperature",
"TopP": "top_p",
"TopK": "top_k",
"MinP": "min_p",
"Seed": "seed",
"StopPrompts": "stop",
"StopTokenIds": "stop_token_ids",
"BadWords": "bad_words",
"IncludeStopStrInOutput": "include_stop_str_in_output",
"IgnoreEOS": "ignore_eos",
"Tokens": "max_tokens",
"MinTokens": "min_tokens",
"Logprobs": "logprobs",
"PromptLogprobs": "prompt_logprobs",
"SkipSpecialTokens": "skip_special_tokens",
"SpacesBetweenSpecialTokens": "spaces_between_special_tokens",
"TruncatePromptTokens": "truncate_prompt_tokens",
}
sampling_params = SamplingParams(top_p=0.9, max_tokens=200)
for request_field, param_field in request_to_sampling_params.items():
if hasattr(request, request_field):
value = getattr(request, request_field)
if value not in (None, 0, [], False):
setattr(sampling_params, param_field, value)
# Structured-output decoding: use Grammar field to pass JSON schema or BNF
if HAS_GUIDED_DECODING and request.Grammar:
try:
json.loads(request.Grammar) # valid JSON = JSON schema
sampling_params.structured_outputs = StructuredOutputsParams(json=request.Grammar)
except json.JSONDecodeError:
sampling_params.structured_outputs = StructuredOutputsParams(grammar=request.Grammar)
# Extract image paths and process images
prompt = request.Prompt
image_paths = request.Images
image_data = [self.load_image(img_path) for img_path in image_paths]
videos_path = request.Videos
video_data = [self.load_video(video_path) for video_path in videos_path]
# If tokenizer template is enabled and messages are provided instead of prompt, apply the tokenizer template
if not request.Prompt and request.UseTokenizerTemplate and request.Messages:
messages_dicts = self._messages_to_dicts(request.Messages)
template_kwargs = {"tokenize": False, "add_generation_prompt": True}
# Pass tools for tool calling
if request.Tools:
try:
template_kwargs["tools"] = json.loads(request.Tools)
except json.JSONDecodeError:
pass
# Enable thinking mode if requested
if request.Metadata.get("enable_thinking", "").lower() == "true":
template_kwargs["enable_thinking"] = True
try:
prompt = self.tokenizer.apply_chat_template(messages_dicts, **template_kwargs)
except TypeError:
# Some tokenizers don't support tools/enable_thinking kwargs — retry without them
prompt = self.tokenizer.apply_chat_template(
messages_dicts, tokenize=False, add_generation_prompt=True
)
# Generate text using the LLM engine
request_id = random_uuid()
print(f"Generating text with request_id: {request_id}", file=sys.stderr)
multi_modal_data = {}
if image_data:
multi_modal_data["image"] = image_data
if video_data:
multi_modal_data["video"] = video_data
outputs = self.llm.generate(
{
"prompt": prompt,
"multi_modal_data": multi_modal_data if multi_modal_data else None,
},
sampling_params=sampling_params,
request_id=request_id,
)
# Stream the results
generated_text = ""
generated_token_ids: list[int] = []
last_output = None
# Tool-parsing strategy decision (made once, before the loop):
#
# When a tool parser is active, the model's raw tool-call markup
# (e.g. <tool_call>...) must not be streamed verbatim as delta.content
# — clients would see the unparsed syntax. Two paths:
#
# (A) native streaming via parser.extract_tool_calls_streaming. All
# concrete tool parsers shipped with vLLM 0.23+ implement this
# (Granite4, Qwen3Coder, DeepSeekV31, Jamba, Ernie45, Hermes,
# llama3_json, mistral, …). The parser decides per-delta whether
# to emit content or suppress tool-call markup, and emits a
# structured DeltaMessage(tool_calls=[...]) when a call is ready.
# (B) buffer fallback — used only when the parser surprisingly lacks
# the streaming method or it raises mid-stream. The post-loop
# extract_tool_calls assembles the final chat_delta. Same correctness
# guarantee as a non-streaming response, at the cost of a delayed
# final chunk.
has_tool_parser = bool(self.tool_parser_cls and request.Tools)
tp_instance = None
tp_request = None
native_streaming = False
native_streaming_error = False
if has_tool_parser:
try:
tools_for_parser = json.loads(request.Tools)
except json.JSONDecodeError:
tools_for_parser = []
try:
tp_instance = self.tool_parser_cls(self.tokenizer, tools=tools_for_parser)
except TypeError:
tp_instance = self.tool_parser_cls(self.tokenizer)
# Build a minimal ChatCompletionRequest so the streaming method
# sees the tools list. We do not need any other request fields —
# parsers only read .tools (and sometimes .tool_choice, which we
# leave at default).
try:
from vllm.entrypoints.openai.chat_completion.protocol import (
ChatCompletionRequest as _CCR,
)
tp_request = _CCR(
model="local",
messages=[{"role": "user", "content": ""}],
tools=tools_for_parser or None,
)
except Exception as e:
print(f"Could not build ChatCompletionRequest for streaming parser: {e}",
file=sys.stderr)
tp_request = None
native_streaming = (
tp_request is not None
and hasattr(tp_instance, "extract_tool_calls_streaming")
)
try:
async for request_output in outputs:
iteration_text = request_output.outputs[0].text
last_output = request_output
if streaming:
delta_iteration_text = iteration_text.removeprefix(generated_text)
new_token_ids = list(request_output.outputs[0].token_ids)
delta_token_ids = new_token_ids[len(generated_token_ids):]
if not has_tool_parser:
# Plain streaming — unchanged from pre-tool-parser path.
yield backend_pb2.Reply(
message=bytes(delta_iteration_text, encoding='utf-8'),
chat_deltas=[backend_pb2.ChatDelta(content=delta_iteration_text)],
)
elif native_streaming and not native_streaming_error:
# (A) Native vLLM extract_tool_calls_streaming.
try:
msg = tp_instance.extract_tool_calls_streaming(
previous_text=generated_text,
current_text=iteration_text,
delta_text=delta_iteration_text,
previous_token_ids=generated_token_ids,
current_token_ids=new_token_ids,
delta_token_ids=delta_token_ids,
request=tp_request,
)
except Exception as e:
print(f"Streaming tool parser error (falling back to "
f"buffer for the rest of the stream): {e}",
file=sys.stderr)
native_streaming_error = True
msg = None
if msg is not None:
tc_protos = []
for tc in (msg.tool_calls or []):
fn = tc.function or None
tc_protos.append(backend_pb2.ToolCallDelta(
index=tc.index,
id=tc.id or "",
name=(fn.name if fn and fn.name else "") or "",
arguments=(fn.arguments if fn and fn.arguments else "") or "",
))
cd_kwargs = {}
if msg.content:
cd_kwargs["content"] = msg.content
if msg.reasoning:
cd_kwargs["reasoning_content"] = msg.reasoning
if tc_protos:
cd_kwargs["tool_calls"] = tc_protos
if cd_kwargs:
yield backend_pb2.Reply(
message=bytes(msg.content or "", encoding='utf-8'),
chat_deltas=[backend_pb2.ChatDelta(**cd_kwargs)],
)
# (B) buffer fallback — emit nothing during the stream.
# The post-loop extract_tool_calls block builds the final chunk.
# Keep track of text + token_ids generated
generated_text = iteration_text
generated_token_ids = list(request_output.outputs[0].token_ids)
finally:
await outputs.aclose()
# Remove the image files from /tmp folder
for img_path in image_paths:
try:
os.remove(img_path)
except Exception as e:
print(f"Error removing image file: {img_path}, {e}", file=sys.stderr)
# Parse reasoning and tool calls from final text using vLLM's native parsers
content = generated_text
reasoning_content = ""
tool_calls_proto = []
if self.reasoning_parser_cls:
try:
rp = self.reasoning_parser_cls(self.tokenizer)
r, c = rp.extract_reasoning(generated_text, request=None)
reasoning_content = r or ""
content = c if c is not None else generated_text
except Exception as e:
print(f"Reasoning parser error: {e}", file=sys.stderr)
# When (A) native streaming ran cleanly, per-delta yields above already
# delivered everything — do NOT extract again on the full text or we'd
# duplicate content/tool_calls into the final chunk.
if has_tool_parser and not (native_streaming and not native_streaming_error):
try:
tp = tp_instance
if tp is None:
# Defensive: tp_instance build failed earlier; reconstruct.
tools = json.loads(request.Tools)
try:
tp = self.tool_parser_cls(self.tokenizer, tools=tools)
except TypeError:
tp = self.tool_parser_cls(self.tokenizer)
info = tp.extract_tool_calls(content, request=None)
if info.tools_called:
content = info.content or ""
for i, tc in enumerate(info.tool_calls):
tool_calls_proto.append(backend_pb2.ToolCallDelta(
index=i,
id=tc.id,
name=tc.function.name,
arguments=tc.function.arguments,
))
except Exception as e:
print(f"Tool parser error: {e}", file=sys.stderr)
elif native_streaming and not native_streaming_error:
# Per-delta path already emitted content + tool_calls; the final
# chat_delta should carry only metadata (token counts, logprobs).
content = ""
# Extract token counts
prompt_tokens = 0
completion_tokens = 0
if last_output is not None:
try:
prompt_tokens = len(last_output.prompt_token_ids or [])
except Exception:
pass
try:
completion_tokens = len(last_output.outputs[0].token_ids or [])
except Exception:
pass
# Extract logprobs if requested
logprobs_bytes = b""
if last_output is not None and request.Logprobs > 0:
try:
lp = last_output.outputs[0].logprobs
if lp:
logprobs_data = {"content": []}
for token_lp_dict in lp:
if token_lp_dict:
first_tok_id, first_lp = next(iter(token_lp_dict.items()))
logprobs_data["content"].append({
"token": getattr(first_lp, "decoded_token", str(first_tok_id)),
"logprob": first_lp.logprob,
})
logprobs_bytes = json.dumps(logprobs_data).encode("utf-8")
except Exception as e:
print(f"Logprobs extraction error: {e}", file=sys.stderr)
chat_delta = backend_pb2.ChatDelta(
content=content,
reasoning_content=reasoning_content,
tool_calls=tool_calls_proto,
)
if streaming:
# Final chunk with structured data.
#
# If we used the buffer fallback (has_tool_parser=True AND native
# streaming did NOT run cleanly) and the parser found no tool call,
# flush the buffered content as ONE content delta — and clear the
# final chat_delta's content so the metadata chunk does not repeat
# what we just sent. This is the plain-text-with-tool-parser path.
buffered_fallback = (
has_tool_parser
and not (native_streaming and not native_streaming_error)
)
if buffered_fallback and not tool_calls_proto and content:
yield backend_pb2.Reply(
message=bytes(content, encoding='utf-8'),
chat_deltas=[backend_pb2.ChatDelta(content=content)],
)
chat_delta = backend_pb2.ChatDelta(
reasoning_content=reasoning_content,
tool_calls=tool_calls_proto,
)
yield backend_pb2.Reply(
message=b"",
prompt_tokens=prompt_tokens,
tokens=completion_tokens,
chat_deltas=[chat_delta],
logprobs=logprobs_bytes,
)
return
# Non-streaming: single Reply with everything
yield backend_pb2.Reply(
message=bytes(content, encoding='utf-8'),
prompt_tokens=prompt_tokens,
tokens=completion_tokens,
chat_deltas=[chat_delta],
logprobs=logprobs_bytes,
)
def load_image(self, image_path: str):
"""
Load an image from the given file path or base64 encoded data.
Args:
image_path (str): The path to the image file or base64 encoded data.
Returns:
Image: The loaded image.
"""
try:
image_data = base64.b64decode(image_path)
image = Image.open(io.BytesIO(image_data))
return image
except Exception as e:
print(f"Error loading image {image_path}: {e}", file=sys.stderr)
return None
def load_video(self, video_path: str):
"""
Load a video from the given file path.
Args:
video_path (str): The path to the image file.
Returns:
Video: The loaded video.
"""
try:
timestamp = str(int(time.time() * 1000)) # Generate timestamp
p = os.path.join(tempfile.gettempdir(), f"vl-{timestamp}.data")
with open(p, "wb") as f:
f.write(base64.b64decode(video_path))
video = VideoAsset(name=p).np_ndarrays
os.remove(p)
return video
except Exception as e:
print(f"Error loading video {video_path}: {e}", file=sys.stderr)
return None
async def serve(address):
# Start asyncio gRPC server
server = grpc.aio.server(migration_thread_pool=futures.ThreadPoolExecutor(max_workers=MAX_WORKERS),
options=[
('grpc.max_message_length', 50 * 1024 * 1024), # 50MB
('grpc.max_send_message_length', 50 * 1024 * 1024), # 50MB
('grpc.max_receive_message_length', 50 * 1024 * 1024), # 50MB
],
interceptors=get_auth_interceptors(aio=True),
)
# Add the servicer to the server
backend_pb2_grpc.add_BackendServicer_to_server(BackendServicer(), server)
# Bind the server to the address
server.add_insecure_port(address)
# Gracefully shutdown the server on SIGTERM or SIGINT
loop = asyncio.get_event_loop()
for sig in (signal.SIGINT, signal.SIGTERM):
loop.add_signal_handler(
sig, lambda: asyncio.ensure_future(server.stop(5))
)
# Start the server
await server.start()
print("Server started. Listening on: " + address, file=sys.stderr)
# Wait for the server to be terminated
await server.wait_for_termination()
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="Run the gRPC server.")
parser.add_argument(
"--addr", default="localhost:50051", help="The address to bind the server to."
)
args = parser.parse_args()
asyncio.run(serve(args.addr))