Files
LocalAI/backend/python
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
..
2026-04-12 08:51:30 +02:00
2026-04-12 08:51:30 +02:00
2026-04-12 08:51:30 +02:00
2026-04-12 08:51:30 +02:00
2026-03-30 00:47:27 +02:00
2026-04-12 08:51:30 +02:00
2026-04-12 08:51:30 +02:00

Python Backends for LocalAI

This directory contains Python-based AI backends for LocalAI, providing support for various AI models and hardware acceleration targets.

Overview

The Python backends use a unified build system based on libbackend.sh that provides:

  • Automatic virtual environment management with support for both uv and pip
  • Hardware-specific dependency installation (CPU, CUDA, Intel, MLX, etc.)
  • Portable Python support for standalone deployments
  • Consistent backend execution across different environments

Available Backends

Core AI Models

  • transformers - Hugging Face Transformers framework (PyTorch-based)
  • vllm - High-performance LLM inference engine
  • mlx - Apple Silicon optimized ML framework

Audio & Speech

  • coqui - Coqui TTS models
  • faster-whisper - Fast Whisper speech recognition
  • kitten-tts - Lightweight TTS
  • mlx-audio - Apple Silicon audio processing
  • chatterbox - TTS model
  • kokoro - TTS models

Computer Vision

  • diffusers - Stable Diffusion and image generation
  • mlx-vlm - Vision-language models for Apple Silicon
  • rfdetr - Object detection models

Specialized

  • rerankers - Text reranking models

Quick Start

Prerequisites

  • Python 3.10+ (default: 3.10.18)
  • uv package manager (recommended) or pip
  • Appropriate hardware drivers for your target (CUDA, Intel, etc.)

Installation

Each backend can be installed individually:

# Navigate to a specific backend
cd backend/python/transformers

# Install dependencies
make transformers
# or
bash install.sh

# Run the backend
make run
# or
bash run.sh

Using the Unified Build System

The libbackend.sh script provides consistent commands across all backends:

# Source the library in your backend script
source $(dirname $0)/../common/libbackend.sh

# Install requirements (automatically handles hardware detection)
installRequirements

# Start the backend server
startBackend $@

# Run tests
runUnittests

Hardware Targets

The build system automatically detects and configures for different hardware:

  • CPU - Standard CPU-only builds
  • CUDA - NVIDIA GPU acceleration (supports CUDA 12/13)
  • Intel - Intel XPU/GPU optimization
  • MLX - Apple Silicon (M1/M2/M3) optimization
  • HIP - AMD GPU acceleration

Target-Specific Requirements

Backends can specify hardware-specific dependencies:

  • requirements.txt - Base requirements
  • requirements-cpu.txt - CPU-specific packages
  • requirements-cublas12.txt - CUDA 12 packages
  • requirements-cublas13.txt - CUDA 13 packages
  • requirements-intel.txt - Intel-optimized packages
  • requirements-mps.txt - Apple Silicon packages

Configuration Options

Environment Variables

  • PYTHON_VERSION - Python version (default: 3.10)
  • PYTHON_PATCH - Python patch version (default: 18)
  • BUILD_TYPE - Force specific build target
  • USE_PIP - Use pip instead of uv (default: false)
  • PORTABLE_PYTHON - Enable portable Python builds
  • LIMIT_TARGETS - Restrict backend to specific targets

Example: CUDA 12 Only Backend

# In your backend script
LIMIT_TARGETS="cublas12"
source $(dirname $0)/../common/libbackend.sh

Example: Intel-Optimized Backend

# In your backend script
LIMIT_TARGETS="intel"
source $(dirname $0)/../common/libbackend.sh

Development

Adding a New Backend

  1. Create a new directory in backend/python/
  2. Copy the template structure from common/template/
  3. Implement your backend.py with the required gRPC interface
  4. Add appropriate requirements files for your target hardware
  5. Use libbackend.sh for consistent build and execution

Testing

# Run backend tests
make test
# or
bash test.sh

Building

# Install dependencies
make <backend-name>

# Clean build artifacts
make clean

Architecture

Each backend follows a consistent structure:

backend-name/
├── backend.py          # Main backend implementation
├── requirements.txt    # Base dependencies
├── requirements-*.txt  # Hardware-specific dependencies
├── install.sh         # Installation script
├── run.sh            # Execution script
├── test.sh           # Test script
├── Makefile          # Build targets
└── test.py           # Unit tests

Troubleshooting

Common Issues

  1. Missing dependencies: Ensure all requirements files are properly configured
  2. Hardware detection: Check that BUILD_TYPE matches your system
  3. Python version: Verify Python 3.10+ is available
  4. Virtual environment: Use ensureVenv to create/activate environments

Contributing

When adding new backends or modifying existing ones:

  1. Follow the established directory structure
  2. Use libbackend.sh for consistent behavior
  3. Include appropriate requirements files for all target hardware
  4. Add comprehensive tests
  5. Update this README if adding new backend types