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Since apache#15413, DenseLiveDocs and SparseLiveDocs fall through to the per-bit generic loop in copyOf. Add toFixedBitSet to the LiveDocs interface so copyOf can bulk-copy with one instanceof check instead of walking every document.
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Forgot the benchmark CopyOfBenchmarkAMD EPYC 7R32 (c5a.2xlarge), JDK 25, 3 forks, 5 iters x 3s. DenseLiveDocs:
SparseLiveDocs:
Generic Bits fallback (unchanged):
SoftDeletesReaderBenchmarkSame hardware setup.
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michaeljmarshall
approved these changes
Sep 3, 2026
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| @Setup(Level.Trial) | ||
| public void setup() throws Exception { | ||
| tempDir = Path.of(System.getProperty("java.io.tmpdir"), "softdel-bench-" + System.nanoTime()); |
Replace java.io.File teardown with IOUtils.rm() and apply google-java-format fixes.
Now that apache#16593 is merged, replace per-doc loop with bulk applyMask as suggested by review.
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After LiveDocs interface was introduced in #15413, FixedBitSet.copyOf fell to per-bit loop execution instead of using the specialized fast paths in Dense/SparseLiveDocs.
This PR addresses that by introducing a toFixedBitSet() method on LiveDocs and a dedicated check in copyOf.
Since there are only two implementations of LiveDocs, both final, the dispatch is bimorphic and inlineable.
copyOf bytecode goes from 90 to 113 bytes, well under the 325-byte FreqInlineSize threshold.
I've included a JMH benchmark and an end-to-end benchmark that measures the impact on SoftDeletesDirectoryReaderWrapper.
Alternative to #16282 which found the same gap but used a different approach.