f74f0a557f
Radix insert can reach the pending-backup/stale-tail split probe on only a subset of CP ranks. The previous opportunistic ack drain called writing_check(), which may issue a scalar write-visibility collective while other ranks are polling inflight transfer state with a different tensor shape. That ordering mismatch matches the observed Gloo 4-vs-2 abort after CP_HICACHE_FALLBACK insert_deferred_pending_backup_split logs. This keeps the split probe local and conservative: it leaves ready write acks queued and lets the globally ordered scheduler/cache-event path drain them. The regression test locks the contract by making any collective from the pending-split probe fail. Constraint: CP radix insert/pending-split probing is not globally ordered across ranks. Rejected: Drain ready write acks from the split probe | can interleave with scheduler poll collectives and corrupt distributed collective ordering. Confidence: high Scope-risk: narrow Directive: Do not call writing_check() or any CP/TP collective from radix pending-split probes; drain write acks only from globally ordered paths. Tested: Remote cjy container: PYTHONPATH=python python -m pytest -q test/registered/unit/mem_cache/test_cp_hicache_metadata.py => 126 passed, 21 warnings. Tested: Remote cjy container: python -m py_compile python/sglang/srt/mem_cache/hiradix_cache.py => PY_COMPILE_OK. Not-tested: Full ETE prefill/decode replay after this change. Co-authored-by: OmX <omx@oh-my-codex.dev>
Registered Tests
Tests under this directory are auto-discovered by run_suite.py via CI registration decorators.
Where Should I Put My New Test?
No server / engine launch required
| What you're testing | Directory | Requires |
|---|---|---|
| Component logic in isolation (cache, scheduler, config, parser, etc.) | unit/<module>/ |
CPU or GPU |
| CUDA kernel correctness | kernels/ |
GPU |
Server / engine launch required (E2E)
| What you're testing | Directory | Requires |
|---|---|---|
| Model inference correctness | models/, 4-gpu-models/, 8-gpu-models/ |
GPU |
| Feature-specific (OpenAI API, LoRA, speculative, distributed, VLM, etc.) | openai_server/, lora/, spec/, distributed/, ... |
GPU |
| Benchmarks (performance, accuracy, stress) | benchmark/ |
GPU |
| Platform-specific | amd/, ascend/ |
Vendor GPU |
See unit/README.md for unit test conventions.