Async MLA/index prefetch is a scheduling optimization, not the correctness contract for target current reuse. Tiny cache-hit suffixes can skip async prefetcher creation while target partial-current reuse still composes page-slot prefix materialization with current KV rows synchronously. CP HiCache radix/device accounting now treats retained valid-tail pages as physical page spans so allocator state stays consistent when logical cache keys are shorter than the retained page. Constraint: CP shared KV ownership and HiCache residency are page-granular while request-visible cache lengths remain valid-token lengths. Constraint: Async prefetch can hang or regress on large-prefix tiny-extend traffic and must not be required for current reuse. Rejected: Treat missing prefetcher as fail-fast for target partial-current reuse | disabled useful current reuse and broke tiny-prefix/tiny-suffix traffic. Rejected: Keep async prefetcher object with synchronous consume mode | conflates prefetch object existence with current-layer correctness and hides fallback semantics. Confidence: medium Scope-risk: moderate Directive: Do not make current-only or target partial-current reuse depend on MLA/index prefetcher creation; prefetcher objects mean async next-layer work exists. Tested: Remote g0034 container py_compile for touched modules. Tested: Remote g0034 PYTHONPATH=python python -m pytest -q test/registered/unit/mem_cache/test_cp_shared_kv_runtime.py -> 73 passed. Tested: Remote g0034 PYTHONPATH=python python -m pytest -q test/registered/unit/mem_cache/test_cp_hicache_metadata.py -> 90 passed. Not-tested: Latest full ETE traffic run with GLM-5.1 CP HiCache after this commit. Not-tested: CUDA kernel-level performance impact of synchronous no-prefetch partial-current compose.
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.