lagent

A lightweight framework for building LLM-based agents

open-sourceagent-frameworks
2.2k
Stars
+8
Stars/month
0
Releases (6m)

Star Growth

2.2k2.2k2.3kMar 27Apr 1

Overview

Lagent is a lightweight Python framework specifically designed for building LLM-based agents and multi-agent systems. Inspired by PyTorch's design philosophy, it uses a neural network layers analogy to make agent workflows more intuitive and Pythonic. The framework centers around AgentMessage objects for communication between agents and provides built-in memory management that automatically stores input and output messages during each forward pass. Lagent simplifies the creation of complex multi-agent applications by allowing developers to focus on defining message passing between agent layers rather than low-level infrastructure concerns. The framework supports integration with various LLM backends including VLLM and popular models like Qwen, making it flexible for different deployment scenarios. With its hook system (pre_hooks and post_hooks), developers can customize agent behavior at different stages of execution. The framework's lightweight nature and clear abstractions make it particularly suitable for researchers and developers who want to rapidly prototype and deploy agent-based systems without dealing with complex boilerplate code.

Deep Analysis

Key Differentiator

vs LangChain/CrewAI: PyTorch-inspired design with intuitive layer composition, dual sync/async interfaces, and built-in session-isolated memory for concurrent agent workloads

Capabilities

  • Lightweight multi-agent LLM framework with message-passing
  • Memory management with session isolation for concurrency
  • Both synchronous and asynchronous operation modes
  • Custom aggregator and flexible output formatting
  • Action executors with hooks for message conversion
  • Self-refinement workflows (blogging, content improvement)

🔗 Integrations

InternLM2Qwen2GPT-4oLMDeployvLLMBing Search

Best For

  • Multi-agent workflows with iterative self-refinement
  • Research with InternLM/Qwen models and custom agents

Not Ideal For

  • Simple single-turn chatbots
  • Teams primarily using commercial LLM APIs

Languages

Python

Deployment

Python library (pip)localdistributed (vLLM tensor parallelism)

Known Limitations

  • Requires explicit session_id management for concurrent use
  • Async components must match (async LLM with async executors)
  • Tool compatibility limited to registered actions
  • Open-source LLM focused, less emphasis on commercial APIs

Pros

  • + PyTorch-inspired design makes agent workflows intuitive for ML practitioners familiar with neural network concepts
  • + Built-in memory management automatically handles message storage and state persistence across agent interactions
  • + Lightweight architecture with clean abstractions that simplify multi-agent system development and reduce boilerplate code

Cons

  • - Limited to source installation only, which may complicate deployment in production environments
  • - Documentation appears minimal based on available information, potentially creating barriers for new users

Use Cases

  • Building conversational AI systems that require multiple specialized agents working together on complex tasks
  • Research prototyping for multi-agent reinforcement learning and collaborative AI experiments
  • Creating intelligent automation workflows where different LLM agents handle specific aspects of a larger process

Getting Started

1. Clone the repository and install from source: `git clone https://github.com/InternLM/lagent.git && cd lagent && pip install -e .` 2. Set up an LLM backend like VllmModel with your chosen model (e.g., Qwen2-7B-Instruct) and configure parameters 3. Create your first agent by instantiating the Agent class with your LLM and system prompt, then send AgentMessage objects to interact with it

Compare lagent