ASpec: A High-Throughput Training Framework for Speculative Decoding Draft Models

ASpec is a high-throughput training framework for speculative decoding draft models, built from the TorchSpec codebase with optimized attention, fused kernels and selective head/loss computation. On a Qwen3-8B 4K run, Draft-only training reaches 15,256.44 input tokens/s on one GPU, 1.96× TorchSpec, while the 8-GPU online steady window hits 77,721.37 tokens/s, 2.28× TorchSpec. It supports DSpark, DFlash, EAGLE3/4 and native MTP drafts, with Qwen3-8B and Ling tiny quickstarts.