lleaves 🍃

A LLVM-based compiler for LightGBM decision trees.

lleaves converts trained LightGBM models to optimized machine code, speeding-up prediction by ≥10x.

Example

lgbm_model = lightgbm.Booster(model_file="NYC_taxi/model.txt")
%timeit lgbm_model.predict(df)
# 12.77s

llvm_model = lleaves.Model(model_file="NYC_taxi/model.txt")
llvm_model.compile()
%timeit llvm_model.predict(df)
# 0.90s 

Why lleaves?

• Speed: Both low-latency single-row prediction and high-throughput batch-prediction.
• Drop-in replacement: The interface of lleaves.Model is a subset of LightGBM.Booster.
• Dependencies: llvmlite and numpy. LLVM comes statically linked.

Installation

pip install lleaves or uv add lleaves (Linux and MacOS only).

Benchmarks

Ran on a dedicated Intel i7-4770 Haswell, 4 cores. Stated runtime is the minimum over 20.000 runs.

Dataset: NYC-taxi

mostly numerical features.

Dataset: MTPL2

mix of categorical and numerical features.

Advanced Usage

To avoid expensive recompilation, you can call lleaves.Model.compile() and pass a cache=<filepath> argument. This will store an ELF (Linux) / Mach-O (macOS) file at the given path when the method is first called. Subsequent calls of compile(cache=<same filepath>) will skip compilation and load the stored binary file instead. For more info, see docs.

To eliminate any Python overhead during inference you can link against this generated binary. For an example of how to do this see benchmarks/c_bench/. The function signature might change between major versions.

Development

High-level explanation of the inner workings of the lleaves compiler: link

# Using uv (recommended)
uv venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
uv pip install -e ".[dev,test]"
pre-commit install
./benchmarks/data/setup_data.sh
pytest -k "not benchmark"

Alternative with pip:

python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
pip install -e ".[dev,test]"
pre-commit install
./benchmarks/data/setup_data.sh
pytest -k "not benchmark"

Cite

If you're using lleaves for your research, I'd appreciate if you could cite it. Use:

@software{Boehm_lleaves,
  author = {Boehm, Simon},
  title = {lleaves},
  url = {https://github.com/siboehm/lleaves},
  license = {MIT},
}