Files
sglang/test/registered/unit
leavelet 1d630def95 Fix CP HiCache load_cp owner-pattern mismatch (cache-hit corruption)
In CP=8 + NSA-shared-KV + HiCache disagg-prefill, cache-hit prefill produced
incoherent decode output. Cold prefill on CP was correct; pure CP without
HiCache was correct. The bug lived at the HiCache load_cp / device-alloc
interface.

Root cause: cache_controller.load_cp called the plain
mem_pool_device_allocator.alloc(logical_len), which returns logical pages
with no CP owner-pattern preservation. Cold prefill instead uses
alloc_extend_compute_owner with a zigzag owner pattern from
build_in_seq_page_compute_owners. The saved CpHiCacheNodeMetadata.owned_positions
records WHICH POSITIONS in the write-time alloc were owned by this rank. At
load time, those same positions are applied to a new alloc whose per-position
owner pattern is arbitrary -- each rank loads its host bytes into physical
slots whose corresponding logical page is owned by a DIFFERENT rank.
Attention's materialize_shared_token_kv_buffer reads from the owner's
physical slot, which was never loaded. Result: garbage.

Fix:
- CpHiCacheNodeMetadata gains two required fields: page_owners (int8 per
  logical page, identical on all CP ranks) and page_size. __post_init__
  validates; split() bisects page_owners by page index with a page-alignment
  check.
- _write_cp derives page_owners from device_indices (page-first slot of each
  page -> logical page id -> layout.owner_for_logical_pages) and stores in
  both metadata-construction sites (zero-owned and normal).
- New CPSharedPagedTokenToKVPoolAllocator.alloc_pages_with_owners() reuses
  _select_compute_owner_pages (with its tai-kernel fast path) and returns
  page-contiguous token locs whose per-page owner sequence equals the input.
- load_cp now concats page_owners across nodes_to_load and calls
  alloc_pages_with_owners. On None (lane exhausted) the caller hits the
  retry-with-eviction path; further failure returns None and degrades to
  cache miss. No silent fallback to plain alloc -- that recreated the bug.
- load_back retry path now calls _evict_for_compute_owner_lanes (module-top
  import) instead of plain evict(); this targets the deficit lane and gives
  the next alloc attempt a chance to satisfy it.
- envs import moved to module top in cache_controller.py per code-review
  feedback. Removed an over-defensive owned_check.all().item() in load_cp
  that would have re-introduced the host-sync anti-pattern 97a9f850c
  removed -- the invariant is already guaranteed by alloc_pages_with_owners.

Tests: 40 existing CpHiCacheNodeMetadata constructions migrated to pass the
new required fields. 9 new metadata tests (validators + split page-alignment).
10 new allocator tests in test_alloc_pages_with_owners.py covering input-order
preservation, lane exhaustion, release_pages fallback, debug-mode invariant.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-27 00:01:39 +08:00
..

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

  1. Find the source file under python/sglang/srt/.
  2. 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
    
  3. 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")
    
  4. Run locally:
    pytest test/registered/unit/ -v            # all unit tests
    pytest test/registered/unit/mem_cache/ -v  # one module
    
  5. 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() or Engine(...).
  • No model weight loading.
  • Use CustomTestCase (from sglang.test.test_utils, adds CI retry).
  • Use unittest.mock for dependencies that are expensive to construct.