Forward-merge release/26.10 into main - #2583
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This PR replaces [cuVS-Lucene #195](NVIDIA/cuvs-lucene#195) as cuVS-Lucene has been merged into cuVS. This PR builds on the out-of-core host-streaming refactor from #2476 by @nvzm123. This PR subsumes #2476 to avoid stacking the PRs. On top of #2476, this PR adds the following. **Improvements** - Native flat buffering: stream vectors directly into a native host matrix during indexing instead of buffering them as a heap List<float[]>, cutting peak host memory from ~2x to ~1x and eliminating the per-vector matrix-assembly copy. Opt-in; requires all input vectors to be indexed in the original order, i.e. not supported for sorted, merged, or filtered index segments; not currently supported for segments with quantized fields. - Parallelized CAGRA-to-HNSW graph conversion: materializing the CAGRA adjacency into on-heap NeighborArrays was a serial per-node loop; parallelized under the existing `writerThreads` knob. - Parallelized level-0 HNSW graph serialization: level-0 (all N nodes) is now delta/VInt-encoded in parallel across memory-bounded waves of threads, then concatenated to the `IndexOutput` in node order according to on-disk format in the serial path. **New example: OptimizedCagraHnswBuildExample** A reference pattern for building a large accelerated HNSW index with all ingest- and build-side optimizations, showcasing: - Streaming, prefetched, bounded-memory ingestion: open the source file once, read it front-to-back in large sequential chunks; hold at most two chunks in memory; fill the next chunk on a background thread while the ingest thread drains the current one, hiding disk read behind indexing; unpack into a caller-reused float[] allocation (no per-vector allocation, safe because Lucene copies the value eagerly inside `addDocument`). - Native flat buffering sized exactly to each segment's vector count via `withNumInputVectors`, avoiding the heap-buffered assembly copy. - Overlapping multi-segment build: - Default: K single-segment passes appended to one directory; peak host memory is one slice (N/K). - Overlapped: a bounded pool (`PIPELINE_DEPTH`) builds segments concurrently into their own directories with the GPU commit serialized on a semaphore (ingest overlaps a prior segment's GPU commit), then combines the finished per-segment indexes by hardlinking their files into the final directory via `HardlinkCopyDirectoryWrapper` + `addIndexes` (no bulk copy of vector data). Peak host memory is up to `PIPELINE_DEPTH * N / K`. - An `enableRMMAsyncMemory()` call (with a note that it must not be used with CPU-only codecs) to opt-in to RMM-managed memory resources, plus exposing the primary tuning knobs (withMaxConn, withBeamWidth, withCuvsDistanceType, withWriterThreads). Authors: - James Xia (https://github.com/jamxia155) - https://github.com/nvzm123 - Igor Motov (https://github.com/imotov) Approvers: - James Lamb (https://github.com/jameslamb) - Igor Motov (https://github.com/imotov) URL: #2481
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SUCCESS - forward-merge complete. |
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Forward-merge triggered by push to release/26.10 that creates a PR to keep main up-to-date. If this PR is unable to be immediately merged due to conflicts, it will remain open for the team to manually merge. See forward-merger docs for more info.