leaveletandClaude Opus 4.8
8f1e85a992
Make CP shared-KV HiCache eviction collective-free and scan-resistant by removing every per-rank wall-clock input from the eviction/admission decisions (any such input desyncs the must-be-replicated victim set / batch across the 8 CP ranks and can deadlock the collective-coupled writeback/load-back). - Replicated logical clock: TreeNode.next_access_time() (a process-global monotonic counter, mirrors mamba/swa's get_last_access_time) replaces time.monotonic() as the source of last_access_time at every radix bump site (radix_cache __init__/match/insert; hiradix CP match/insert/_insert_helper_host; reset() zeroes it). creation_time/pin_expiry intentionally stay wall-clock. Because match/insert events are replicated (reqs broadcast from rank 0 over the replicated tree), last_access_time is now identical on every rank. Unique ints also give a strict total order (no LRU tie ambiguity). No duration arithmetic reads last_access_time, so non-CP LRU is unchanged; mamba/swa use their own TreeNode and are untouched. - CpReplicatedSLRUStrategy = (is_protected[hit>=2], last_access_time, node.id): scan-resistant (cold one-shots stay probationary, evicted before reused/ protected prefixes), recency-within-segment ages out cold (not LFU), node.id is the deterministic total-order tiebreak (heaps never compare TreeNodes). Overridden for CP so it reaches every get_priority eviction site; the host write-admission key _cp_host_evict_key is switched from FIFO-by-id to it. - Co-fixes for the same per-rank-wall-clock class: pin_prefix is forbidden under CP (its pin_expiry victim-eligibility check is per-rank wall-clock; SLRU scan-resistance covers the benefit); the affinity head_age_s admission input is disabled (=0.0, relying on the replicated head_defer_count bound); and a server_args fail-fast guards CP shared-KV against SGLANG_REQ_WAITING_TIMEOUT>0 (its waiting-queue pruning is per-rank wall-clock). Tests: test_evict_policy.py adds TestCpReplicatedSLRUStrategy (scan-resistance, recency, total-order, full ordering) -- 30 passed in the dev-cu13 container; test_radix_cache_unit.py adds logical-clock determinism/total-order tests. 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.