Fine-tune LLM agents with online reinforcement learning
Project description
Fine-tune LLM agents with online reinforcement learning
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LlamaGym
"Agents" originated in reinforcement learning, where they learn by interacting with an environment and receiving a reward signal. However, LLM-based agents today do not learn online (i.e. continuously in real time) via reinforcement.
OpenAI created Gym to standardize and simplify RL environments, but if you try dropping an LLM-based agent into a Gym environment for training, you'd find it's still quite a bit of code to handle LLM conversation context, episode batches, reward assignment, PPO setup, and more.
LlamaGym seeks to simplify fine-tuning LLM agents with RL. Right now, it's a single Agent
abstract class that handles all the issues mentioned above, letting you quickly iterate and experiment with agent prompting & hyperparameters across any Gym environment.
Usage
Fine-tuning an LLM-based agent to play in a Gym-style environment with RL has never been easier! Once you install LlamaGym...
pip install llamagym
First, implement 3 abstract methods on the Agent class:
from llamagym import Agent
class BlackjackAgent(Agent):
def get_system_prompt(self) -> str:
return "You are an expert blackjack player."
def format_observation(self, observation) -> str:
return f"Your current total is {observation[0]}"
def extract_action(self, response: str):
return 0 if "stick" in response else 1
Then, define your base LLM (as you would for any fine-tuning job) and instantiate your agent:
model = AutoModelForCausalLMWithValueHead.from_pretrained("Llama-2-7b").to(device)
tokenizer = AutoTokenizer.from_pretrained("Llama-2-7b")
agent = BlackjackAgent(model, tokenizer, device)
Finally, write your RL loop as usual and simply call your agent to act, reward, and terminate:
env = gym.make("Blackjack-v1")
for episode in trange(5000):
observation, info = env.reset()
done = False
while not done:
action = agent.act(observation) # act based on observation
observation, reward, terminated, truncated, info = env.step(action)
agent.assign_reward(reward) # provide reward to agent
done = terminated or truncated
train_stats = agent.terminate_episode() # trains if batch is full
Some reminders:
- above code snippets are mildly simplified above but a fully working example is available in
examples/blackjack.py
- getting online RL to converge is notoriously difficult so you'll have to mess with hyperparameters to see improvement
- your model may also benefit from a supervised fine-tuning stage on sampled trajectories before running RL (we may add this feature in the future)
- our implementation values simplicity so is not as compute efficient as e.g. Lamorel, but easier to start playing around with
- LlamaGym is a weekend project and still a WIP, but we love contributions!
Relevant Work
- Grounding Large Language Models with Online Reinforcement Learning
- True Knowledge Comes from Practice: Aligning LLMs with Embodied Environments via Reinforcement Learning
Citation
bibtex
@misc{pandey2024llamagym,
title = {LlamaGym: Fine-tune LLM agents with Online Reinforcement Learning},
author = {Rohan Pandey},
year = {2024},
howpublished = {GitHub},
url = {https://github.com/KhoomeiK/LlamaGym}
}
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