In NSA in-seq-split prefill-CP shared-KV the owner builder restarted every
chunk/request at owner 0, starving physical lane 0 -> load-back livelock (g0057:
~64k cp_load_back_owner_lane_capacity_failed + ~4k owner_lane_exhausted). Rotate
the owner/compute assignment by phase=((extend_prefix_len//page_size)+req_index)
%cp_size so chunks/requests/draft pages spread across lanes, keeping owner==compute
(the local_loc_owner_mismatch invariant) by rotating the zigzag compute split by the
same phase. Cache-safe: reload replays recorded page_owners, never recomputes phase.
- owner builder + helpers (cp_owner_lane_phase two-term prefix+req_index,
cp_in_seq_reverse_map, cp_rotated_per_rank_actual_token) in
cp_shared_kv_compute_owner.py
- zigzag compute split, gather-back reverse map, bs>1 torch rerange, last-token
owner, request_phases on NSAContextParallelMetadata, scalar-path + last-token
fail-loud guards in nsa/utils.py
- mqa-logits prefill buffer estimator made rotation-aware (per-request phase) so it
no longer under-sizes the admission budget
- flag SGLANG_CP_SHARED_KV_OWNER_ROTATION (default True; =0 is the legacy escape
hatch -- phase forced to 0 = byte-for-byte legacy, needs no new kernel)
- startup require_tai_kernel_version("0.0.2") gate (utils/common.py, model_runner)
- unit tests (11): tiny-chunk pathology [40,0x7]->[5x8], synchronized-batch spread
[0x8]->[0..7], gather-back reassembly, per-rank-token
Requires tai-kernel >= 0.0.2 (phase-aware in_seq_all_gather_rerange). Reviewed by 3
adversarial agents (owner==compute consistency, gather-back equivalence, integration
safety): SHIP-WITH-NITS, all findings fixed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Unit Tests
Component-level tests that do not launch a server or load model weights. Tests can use CPU or GPU — the key criterion is no server process.
Quick Start
- Find the source file under
python/sglang/srt/. - Create the corresponding test here, mirroring the source tree:
srt/mem_cache/radix_cache.py → unit/mem_cache/test_radix_cache.py srt/sampling/sampling_params.py → unit/sampling/test_sampling_params.py - Register for CI at the top of the file (after imports, before test classes):
from sglang.test.ci.ci_register import register_cpu_ci register_cpu_ci(est_time=5, suite="stage-a-test-cpu") # or: register_cuda_ci(est_time=10, suite="stage-b-test-1-gpu-small") - Run locally:
pytest test/registered/unit/ -v # all unit tests pytest test/registered/unit/mem_cache/ -v # one module - Run with coverage:
# summary pytest test/registered/unit/ --cov --cov-config=.coveragerc -v # PR incremental check (require ≥60% on changed lines) pytest test/registered/unit/ --cov --cov-config=.coveragerc --cov-report=xml diff-cover coverage.xml --compare-branch=origin/main --fail-under=60
Example
"""Unit tests for <module> — no server, no model loading."""
from sglang.test.ci.ci_register import register_cpu_ci
register_cpu_ci(est_time=5, suite="stage-a-test-cpu")
import unittest
from sglang.srt.<module> import TargetClass
from sglang.test.test_utils import CustomTestCase
class TestTargetClass(CustomTestCase):
def test_basic_behavior(self):
obj = TargetClass(...)
self.assertEqual(obj.method(), expected)
if __name__ == "__main__":
unittest.main()
Rules
- No
popen_launch_server()orEngine(...). - No model weight loading.
- Use
CustomTestCase(fromsglang.test.test_utils, adds CI retry). - Use
unittest.mockfor dependencies that are expensive to construct.