21065cdfdf
The repeated-request hang reproduced on g0034 after the cached-prefix request created both MLA and index async prefetchers with prefix_lens=[40320] and extend_lens=[65]. The existing one-page default only blocked sub-page suffixes, so a barely-over-one-page suffix still entered the next-layer collective path before any later forward progress was logged. Raise the default async prefetch extend gate to one page per CP lane while keeping the env override. This only gates async prefetcher object creation; target partial-current reuse still uses the synchronous page-slot compose/current-splice path when no prefetcher exists. Constraint: cp_size=8,page_size=64 repeated prompt had extend_len=65 and hung immediately after has_mla=True has_index=True create_result logs Rejected: Disable partial-current reuse for short extends | that would lose the cache-hit benefit and regress current/full reuse Rejected: Disable all async prefetch by default | broader performance impact than the observed tiny-suffix failure Confidence: medium Scope-risk: moderate Directive: Do not lower the default below one page per CP lane without ETE proof that repeated cache-hit tiny suffixes no longer hang Tested: Remote g0034 container py_compile for touched runtime/prefetch/test files; targeted C22 tests passed 2 tests plus 2 subtests; full test_cp_shared_kv_runtime.py passed 73 tests plus 2 subtests Not-tested: Full multi-node ETE repeated-request run after this threshold change
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.