leavelet
1923fcd67e
The bs=1 MLA/index prefetchers replaced their consume-side trailing-range NCCL all-reduce with the staging exchange: fill current rows straight into this round's staging span (token-KV collapses to one cached index_copy; the index fill kernel is just pointed at the staging page inverse), cp_symm_barrier, then gather ALL current pages — this rank's own included — from the stagings into the prefetched dense buffer. The symm+prefetcher FAIL_FAST is gone. Rank-uniformity moves with it: staging registration now also happens in maybe_create (batch-logical gates, before any per-rank miss can diverge), because with a prefetcher active the sync compose runs only on per-rank misses and its lazy collective registration would hang. A hit/miss divergence itself stays barrier-safe — both the prefetch consume and the sync-compose fallback execute exactly one begin_round + barrier per (layer, kind), and the counting barrier is shape-free (unlike the AR pair it replaces, which would shape-mismatch). Found by the new index test phase: the fill/remap kernel family skips page id 0 as the SGLang dummy page, so a 0-based first staging slot was never written. The staging layout now reserves row 0 (slot of current page i = i + 1) for every kind, matching the convention instead of depending on per-kernel behavior. Launch-path cost: per-(kind,parity) peer pointer tables and the [pool|staging] concatenations are precomputed/cached (identity pinned by holding the pool-table reference); all prefetch descriptors, staging row indices, and mixed_locs are built once per batch. Validated on g0033 8xH200: 151 unit tests; 8-rank byte-exactness for token sync symm (8 layers), index sync symm (4 layers, new phase), and MLA + index prefetch consume_prefix_with_current vs the legacy sync compose. 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.