A Deep Dive into Scaling RL for Code Generation with Synthetic Data and Curricula

Fuente: arXiv
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Main Authors: Sancaktar, Cansu, Zhang, David, Synnaeve, Gabriel, Cohen, Taco
Format: Preprint
Published: 2026
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author Sancaktar, Cansu
Zhang, David
Synnaeve, Gabriel
Cohen, Taco
author_facet Sancaktar, Cansu
Zhang, David
Synnaeve, Gabriel
Cohen, Taco
contents Reinforcement learning (RL) has emerged as a powerful paradigm for improving large language models beyond supervised fine-tuning, yet sustaining performance gains at scale remains an open challenge, as data diversity and structure, rather than volume alone, become the limiting factor. We address this by introducing a scalable multi-turn synthetic data generation pipeline in which a teacher model iteratively refines problems based on in-context student performance summaries, producing structured difficulty progressions without any teacher fine-tuning. Compared to single-turn generation, this multi-turn approach substantially improves the yield of valid synthetic problems and naturally produces stepping stones, i.e. easier and harder variants of the same core task, that support curriculum-based training. We systematically study how task difficulty, curriculum scheduling, and environment diversity interact during RL training across the Llama3.1-8B Instruct and Qwen3-8B Base model families, with additional scaling experiments on Qwen2.5-32B. Our results show that synthetic augmentation consistently improves in-domain code and in most cases out-of-domain math performance, and we provide empirical insights into how curriculum design and data diversity jointly shape RL training dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24202
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Deep Dive into Scaling RL for Code Generation with Synthetic Data and Curricula
Sancaktar, Cansu
Zhang, David
Synnaeve, Gabriel
Cohen, Taco
Machine Learning
Artificial Intelligence
Reinforcement learning (RL) has emerged as a powerful paradigm for improving large language models beyond supervised fine-tuning, yet sustaining performance gains at scale remains an open challenge, as data diversity and structure, rather than volume alone, become the limiting factor. We address this by introducing a scalable multi-turn synthetic data generation pipeline in which a teacher model iteratively refines problems based on in-context student performance summaries, producing structured difficulty progressions without any teacher fine-tuning. Compared to single-turn generation, this multi-turn approach substantially improves the yield of valid synthetic problems and naturally produces stepping stones, i.e. easier and harder variants of the same core task, that support curriculum-based training. We systematically study how task difficulty, curriculum scheduling, and environment diversity interact during RL training across the Llama3.1-8B Instruct and Qwen3-8B Base model families, with additional scaling experiments on Qwen2.5-32B. Our results show that synthetic augmentation consistently improves in-domain code and in most cases out-of-domain math performance, and we provide empirical insights into how curriculum design and data diversity jointly shape RL training dynamics.
title A Deep Dive into Scaling RL for Code Generation with Synthetic Data and Curricula
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2603.24202