Segment 71
This sub-session resolved two production issues: a PD deadlock caused by overlap schedule desync (fixed with --disable-overlap-schedule) and a high-concurrency tool-call corruption traced to the bf16 index-K patch interacting with a race condition in the HiCache index-K read path (mitigated by disabling HiCache). A mass-abort wedge was fixed by handling ABORT messages in the NIXL bootstrap_thread, and pool_configurator.py bf16 sizing was corrected. Extensive A/B testing confirmed fp8 keys produce 0% corruption while bf16 produces 17% under load, ruling out topk-v2, eager decode, and prompt transfer. A persistent heavy multi-turn corruption even with HiCache off remains under investigation, narrowed to decode-side bf16 index-K handling.
Fix PD deadlock by disabling overlap scheduleRoot-cause high-concurrency tool-call corruptionFix mass-abort wedge in NIXL bootstrap_threadFix pool_configurator.py bf16 sizingConduct A/B tests to isolate corruption to bf16 index-K pathInvestigate persistent heavy multi-turn corruption with HiCache off
Chunks
- Two Fronts, One War: Debugging a PD Deadlock and Tool-Call Corruption in Production
- The PD Transfer That Corrupted Everything: Tracing a bf16 Index-K Race Condition Under High Concurrency
- The Art of Systematic Falsification: How a Production Debugging Campaign Isolated a bf16 Index-K Concurrency Bug
- The Missing Gate: How a Race Condition in HiCache Caused Production Corruption in a Disaggregated LLM Serving Stack
- The Anatomy of a Production Debugging Campaign: Tracing bf16 Index-K Corruption Through SGLang's Memory Hierarchy
- The Anatomy of a Production Debugging Marathon: How Six Subagents, Dozens of Experiments, and One Clean A/B Test Unraveled Three Bugs in a Blackwell AI Inference Stack