Cap the typed-structure dictionary in RecordEncoder (maxOwnStructures) - #1145
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kriszyp
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The per-encoder typedStructs dictionary (structon's random-access typed structs) is append-only and pinned on the long-lived primary store. A wide/sparse schema whose records vary by per-field value width mints a distinct structure per shape×width combination and grows the dictionary unbounded, exhausting memory (observed on a bulk-loaded table under replication catch-up). Default maxOwnStructures to 256 (caller-overridable), bounding each dictionary. Bumps structon to ^1.0.6, which adds the cap (uncapped by default). Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Summary
Defaults
maxOwnStructuresto 256 inRecordEncoderand bumpsstructonto^1.0.6(which adds the cap). Bounds the per-encoder typed-structure dictionary that was growing unbounded and OOM-ing under shape-heterogeneous data.Purpose
structon's random-access typed-struct dictionary (
typedStructs+ transition trie) is append-only and pinned on the long-lived primary-store encoder/decoder. The encoder branches per field on the value's numeric width (num8/num32/num64, float32/float64) and string kind, so a wide/sparse schema (~hundreds of distinct key-sets) explodes into tens of thousands of structures — and per-table-per-peer dictionaries, multiplied across worker isolates, OOM-crash-looped a production cluster during replication catch-up of a bulk-loaded table.structon@1.0.6adds an opt-inmaxOwnStructurescap (uncapped by default; see HarperFast/structon#4). This wires it on: once the cap is hit, novel shapes fall back to plain msgpack encoding; the read path is untouched so existing/persisted structs stay decodable. 256 is caller-overridable (a table/DBI option can raise it).Where to look
resources/RecordEncoder.ts(options.maxOwnStructures ??= 256beforesuper(options)), plus thestructondep bump. RecordEncoder extends structon'screateStructon(Encoder).Validation
unitTests/resourcessuite passes (687 passing, 0 failing). The cap logic itself is covered by structon's 94-test suite (structon#4), which exercises exactly thiscreateStructon(msgpackr-v2)+maxOwnStructuresusage. Change is a one-line option default, so no dedicated harper unit test added (RecordEncoder isn't standalone-instantiable; the behavior is upstream-tested).v5.0branch + msgpackr1.11.13.🤖 Generated by Claude (Opus 4.7).