Addresses the opus review of the Step A/B compose stack: - FAIL FAST on symm + prefetcher coexistence: the MLA/index prefetchers issue their own per-span collectives and bypass the symm exchange, so letting them coexist would make COMPOSE_SYMM a silent no-op on every prefetch hit (measured "parity" that never ran). maybe_build_current_ page_writer_ranks now raises when a prefetcher is attached or SGLANG_CP_SHARED_KV_ENABLE_MLA_PREFETCH is set. - Arena parity now derives from a monotonic round epoch instead of raw layer_id: EAGLE draft layers reuse decoder layer ids, so id-parity would stop alternating halves (draft L0 -> next forward target L0 lands on the same half) and repeated-id rounds would keep appending into one half. begin_round(layer_id, kind) starts a new round (other half, offsets reset) when the id changes OR a kind repeats; regression test included. - Per-batch writer-ranks cache on the forward batch and a presence flag in the plan key: previously the ~bs x current-pages writer list was rebuilt AND tuple-hashed on every layer per call site, pure launch-path waste. - Rank-uniformity invariant documented at _symm_exchange_current_pages (any per-rank gate must go through a group agreement first) and an actionable arena-overflow message naming SGLANG_CP_SHARED_KV_SYMM_HEAP_MB. Deferred follow-ups (documented in the design doc): factor the two near- clone v2 helpers, single barrier per F-layer (~308us/batch), persistent device-side peer-ptr tables for the gather. 182 targeted tests + 8-rank GPU byte-exactness (v2 and symm) re-validated on g0034 syh-dev-new. Co-Authored-By: Claude Fable 5 <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.