DORA: A Scalable Asynchronous Reinforcement Learning System for Language Model Training
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Abstract (arXiv)
Reinforcement learning (RL) has become a critical paradigm for LLM post-training, yet the rollout phase -- accounting for 50--80% of total step time -- is bottlenecked by skewed generation: long-tailed trajectories indispensable for model performance block the entire training pipeline. Asynchronous training offers a natural remedy by overlapping generation with training, but introduces a fundamental tension between efficiency and algorithmic correctness. We identify three constraints in asynchronous training to preserve convergence: intra-trajectory policy consistency, data integrity, and bounded staleness. Existing approaches fail to intrinsically address the long-tailed trajectory problem, which is further exacerbated by the imbalance characteristic of Mix-of-Experts models, or deviate from the standard RL training formulation, thereby hindering model convergence. Therefore, we propose DORA (Dynamic ORchestration for Asynchronous Rollout), which addresses this challenge through algorithm-system co-design. DORA introduces multi-version streaming rollout, a novel asynchronous paradigm that maintains multiple policy versions concurrently -- simultaneously achieving full bubble elimination without compromising algorithmic constraints. Experimental results demonstrate that our DORA system achieves substantial improvements in throughput -- up to 2--3 times higher than state-of-the-art systems on open-source benchmarks -- without compromising convergence. Furthermore, in large-scale industrial applications with tens of thousands of accelerators, DORA accelerates RL training by 2--4 times compared to synchronous training across various scenarios. The resultant open-source models, LongCat-Flash-Thinking, exhibit competitive performance on complex reasoning benchmarks, matching the capability of most advanced LLMs.
Key facts. Cited by 13 papers in the map (data through 7 Oct 2026). Builds on 44 of its 54 references that are in the map. First posted on arXiv 29 Apr 2026.
Builds on
44 of 54 references.
References · 44
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- 2025DeepSeek-R1: Incentivizing Reasoning Capability in LLMs via Reinforcement Learningcited by 6,146
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Citing papers per year: 2026: 13.
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- 2026Deconstructing Off-Policy Ratios: Entropy-Normalized Trust Regions for Asynchronous Reinforcement Learning24 Jul 2026
- 2026Molt: A Scalable PyTorch-Native Training Framework for Agentic Reinforcement Learning22 Jul 2026
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- 2026Scheduling Mixed RL Rollouts Beyond Prefix Localitycited by 1
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- 2026BRACE: Anchored Bellman-Residual Correction for Stale Critics in Asynchronous RLcited by 0
- 2026DivOPD: Spread Wide, Look Close for Asynchronous On-Policy Distillation of Multi-turn Agentscited by 0
- 2026Where Does Staleness Accumulate? Pool Aware Effective Staleness Control for Asynchronous RL in LLM Post-Trainingcited by 0
- 2026Where Does Staleness Accumulate? Pool Aware Effective Staleness Control for Asynchronous RL in LLM Post-Training29 Sep 2026
- 2026DivOPD: Spread Wide, Look Close for Asynchronous On-Policy Distillation of Multi-turn Agents28 Sep 2026
- 2026BRACE: Anchored Bellman-Residual Correction for Stale Critics in Asynchronous RL9 Sep 2026
- 2026Scheduling Mixed RL Rollouts Beyond Prefix Locality11 Aug 2026
- 2026Reusing Rollouts under Policy Lag: Prefix-Normalized Policy Optimization for LLM Reinforcement Learning2 Aug 2026
- 2026Deconstructing Off-Policy Ratios: Entropy-Normalized Trust Regions for Asynchronous Reinforcement Learning24 Jul 2026