On restart the LMDB index + disk-slab blobs persist, but CpL3Store.from_config built the slot
pools all-free and the GC LRU empty -> the next spill re-hands-out a slot the durable index still
references (clobbers a live blob) and GC never reclaims the carried-over entries. Neither a clean
start nor a durable reload was actually realized.
connect() now applies a cold-start policy BEFORE the bg threads start (the write thread is the sole
pool/GC owner, so the single-threaded reconcile must precede it):
- clear (default): wipe the persisted index + reset the pools/GC -> genuinely empty start (disk
blobs are inert, overwritten lazily on slot reuse).
- load: rebuild this rank's slot free-list + GC LRU from the durable disk blobs. Drive the scan
from the rank's OWN slab file (header-only reads) so it never inspects another rank's slots even
when ranks share a disk; a slot is LIVE iff its blob header parses AND the shared index still maps
that content hash back to this exact slot -> occupy + seed the GC LRU with the durable last_access;
orphan/unwritten slots stay free. Header-only (no payload CRC); reload-time verify-on-read still
fail-softs a torn payload. The L3 durable floor now survives a process restart.
Primitives: CpL3SlotPool.rebuild_from_allocated (O(num_slots) bulk-occupy) + CpL3DiskSlab.read_header
(one aligned block, not the multi-MB slot). Env SGLANG_CP_L3_COLD_START (default "clear"), read in
_maybe_init_cp_l3 and passed to connect(). Tests: 4 cold-start e2e (load rebuilds the floor + no slot
collision after a fresh spill; GC LRU rebuilt; clear starts empty; unknown mode fails loud) + 2 unit
(rebuild_from_allocated, read_header). 23 L3 store/disk/posix tests green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Preallocated disk-slab file per (payload_kind, drive); a page = one contiguous blob
(64B header + gathered payload + pad) in a 4K-aligned slot. O_DIRECT single-transfer
write/read (measured best vs vectored), buffered+fdatasync fallback for FS without O_DIRECT.
write_slot/read_slot convenience + write_aligned/read_into zero-copy (the QD>1 spill/reload
path gathers/scatters straight into the aligned slot buffer). verify-on-read: absent/torn/
foreign slot -> None (a MISS to recompute + reclaim), never a crash. posix_fallocate preallocate.
9/9 unit tests (real temp FS).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
leaveletandClaude Opus 4.8