leavelet
8d73919d02
A long cold-request workload flooded the prefill log (~177MB / 32K lines in 8min, all 8 CP ranks) with cp_host_reservation_plan_insufficient + prepare_write_backup_reservation_failed even though the host pool was <42% used and the writes physically fit. Root cause: _free_room_deficit folds the proactive 20% free-room target (hicache_host_free_room_ratio) into the admission deficit once a lane dips below the 10% trigger. _evict_cp_host_for_write_admission then failed -- and evicted nothing -- whenever it could not reclaim that full 20% target, which is impossible while the residual is locked/pending. The lane never drained, so every subsequent backup re-issued the same impossible demand and re-logged on every tick. The reservation failure is itself a graceful skip, so there is no crash; the symptom is the log storm. Gate write-backup admission on the HARD deficit -- max(0, required-available) over the target and draft lanes (draft_available is 2**62 with no draft pool, a no-op) -- and evict toward the watermark best-effort, admitting whenever the write itself fits. This drains the stuck lane and backs the request up instead of skipping+flooding. The proactive watermark stays as the eviction target (deficit_by_owner unchanged); it is no longer a hard admission gate. The decision is computed from rank-replicated state on the collective-free reserve path, so every CP rank makes the same admit/skip choice (opus-reviewed rank-safe). Also rate-limit the four host-reservation fallback warnings (once per 10s per fallback_name, with a suppressed count) so any genuine exhaustion degrades quietly instead of producing a log storm. 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.