Fix permanent Lucene index corruption under concurrent indexing requests#35
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Fix permanent Lucene index corruption under concurrent indexing requests#35vany0114 wants to merge 1 commit into
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IndexDocuments creates a fresh IndexWriter per request. Lucene allows only one IndexWriter per directory, so two concurrent indexing requests against the same index race: the loser fails with LockObtainFailedException, and under sustained concurrency a torn commit corrupts the segment files permanently (FileNotFoundException: .../_N.si on every subsequent write until the index directory is deleted from disk). Reproduced with 30 concurrent writers x 30 sequential mergeOrUpload requests against a fresh index: 889/900 requests returned 500 and the index remained broken after concurrency stopped. With this change the same load succeeds 900/900 and the index stays healthy. A per-index SemaphoreSlim serializes IndexDocuments per index name; requests against different indexes still run in parallel. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Context
LuceneNetSearchIndexer.IndexDocumentsopens a freshIndexWriterper request. Lucene allows only a singleIndexWriterper directory, so two concurrent indexing requests against the same index race:LockObtainFailedException(HTTP 500), andSystem.IO.FileNotFoundException: Could not find file '.../_N.si'until the index directory is deleted from disk.We hit this in a CI environment where several services index into one shared index: 500 consecutive indexing requests failed after the corruption event, and the index never recovered on its own.
Repro
30 concurrent workers × 30 sequential
mergeOrUploadrequests against a freshly created index:FileNotFoundExceptionon segment files) — the index is permanently broken.Change
A static
ConcurrentDictionary<string, SemaphoreSlim>gatesIndexDocumentsper index name. Writes to the same index are serialized; requests against different indexes still run in parallel. Read paths are untouched.Test plan
dotnet test— unit tests 134/134 pass; integration tests 24/25 (the single failure pre-exists onmainand is unrelated).🤖 Generated with Claude Code