train_qwen3_codeforces_v3.py

# /// script
# dependencies = [
#     "trl>=0.12.0",
#     "peft>=0.7.0",
#     "transformers>=4.36.0",
#     "accelerate>=0.24.0",
#     "datasets",
#     "torch",
# ]
# ///

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

# Load dataset
print("Loading dataset...")
dataset = load_dataset("open-r1/codeforces-cots", "solutions_py_decontaminated", split="train")
print(f"Dataset loaded: {len(dataset)} examples")

# Take subset for training (full dataset is very large)
dataset = dataset.shuffle(seed=42).select(range(min(5000, len(dataset))))
print(f"Using {len(dataset)} examples")

# Create train/eval split
print("Creating train/eval split...")
dataset_split = dataset.train_test_split(test_size=0.1, seed=42)
train_dataset = dataset_split["train"]
eval_dataset = dataset_split["test"]
print(f"Train: {len(train_dataset)} examples")
print(f"Eval: {len(eval_dataset)} examples")

# Training configuration
config = SFTConfig(
    output_dir="qwen3-0.6b-codeforces-sft",
    push_to_hub=True,
    hub_model_id="luiscosio/qwen3-0.6b-codeforces-sft",
    hub_strategy="every_save",
    num_train_epochs=3,
    per_device_train_batch_size=2,
    gradient_accumulation_steps=8,
    gradient_checkpointing=True,
    learning_rate=2e-4,
    logging_steps=10,
    save_strategy="steps",
    save_steps=100,
    save_total_limit=3,
    eval_strategy="steps",
    eval_steps=100,
    warmup_ratio=0.1,
    lr_scheduler_type="cosine",
    bf16=True,
    max_length=2048,
    report_to="none",
)

# LoRA configuration
peft_config = LoraConfig(
    r=16,
    lora_alpha=32,
    lora_dropout=0.05,
    bias="none",
    task_type="CAUSAL_LM",
    target_modules=["q_proj", "k_proj", "v_proj", "o_proj", "gate_proj", "up_proj", "down_proj"],
)

# Initialize and train
print("Initializing trainer...")
trainer = SFTTrainer(
    model="Qwen/Qwen3-0.6B",
    train_dataset=train_dataset,
    eval_dataset=eval_dataset,
    args=config,
    peft_config=peft_config,
)

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

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

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