train_qwen3_codeforces.py

# /// script
# requires-python = ">=3.10"
# dependencies = [
#     "trl>=0.12.0",
#     "peft>=0.7.0",
#     "transformers>=4.36.0",
#     "accelerate>=0.24.0",
#     "trackio",
# ]
# ///

import trackio
from datasets import load_dataset
from peft import LoraConfig
from trl import SFTTrainer, SFTConfig


# Load dataset - use only 20 examples for quick demo
print("📦 Loading dataset...")
full_dataset = load_dataset("open-r1/codeforces-cots", split="train")
# Take only first 20 examples for quick demo
dataset = full_dataset.select(range(20))
print(f"✅ Dataset loaded: {len(dataset)} examples")

# Format the dataset - convert messages to text format for SFT
def format_for_sft(example):
    """Convert messages to a single text format for training."""
    messages = example.get("messages", [])
    text = ""
    for msg in messages:
        role = msg.get("role", "unknown")
        content = msg.get("content", "")
        if role == "system":
            text += f"System: {content}\n\n"
        elif role == "user":
            text += f"User: {content}\n\n"
        elif role == "assistant":
            text += f"Assistant: {content}\n\n"
    return {"text": text.strip()}

print("🔄 Formatting dataset...")
dataset = dataset.map(format_for_sft, remove_columns=dataset.column_names)
print(f"   Formatted to text: {dataset[0]['text'][:200]}...")

# Training configuration
config = SFTConfig(
    # CRITICAL: Hub settings
    output_dir="qwen3-0.6b-codeforces-sft",
    push_to_hub=True,
    hub_model_id="albertlieadrian/qwen3-0.6b-codeforces-sft",
    hub_strategy="every_save",

    # Training parameters - optimized for small dataset demo
    num_train_epochs=3,
    per_device_train_batch_size=2,
    gradient_accumulation_steps=4,
    learning_rate=2e-5,
    max_length=2048,  # Code problems need longer context

    # Logging & checkpointing
    logging_steps=5,
    save_strategy="no",  # Skip saving for quick demo
    save_total_limit=0,

    # Optimization
    warmup_ratio=0.1,
    lr_scheduler_type="cosine",

    # Monitoring
    report_to="trackio",
    project="qwen3-codeforces-demo",
    run_name="20-examples-demo",
)

# LoRA configuration - efficient for 0.6B model
peft_config = LoraConfig(
    r=16,
    lora_alpha=32,
    lora_dropout=0.05,
    bias="none",
    task_type="CAUSAL_LM",
    target_modules=["q_proj", "v_proj"],
)

# Initialize and train
print("🎯 Initializing trainer...")
trainer = SFTTrainer(
    model="Qwen/Qwen3-0.6B",
    train_dataset=dataset,
    formatting_func=lambda x: x["text"],
    args=config,
    peft_config=peft_config,
)

print("🚀 Starting training...")
trainer.train()

print("💾 Pushing to Hub...")
trainer.push_to_hub()

# Finish Trackio tracking
trackio.finish()

print("✅ Complete! Model at: https://huggingface.co/albertlieadrian/qwen3-0.6b-codeforces-sft")