Flaky: Unit Test (Node.js v24) SIGSEGV (exit 139) in schema-change / index-rebuild test group — v24-only

[heskew]

Summary

The Unit Test (Node.js v24) CI job intermittently dies with Segmentation fault (core dumped) → Process completed with exit code 139. It is specific to Node.js v24 — on the same commits, Unit Test (Node.js v22) and Unit Test (Node.js v26) pass every time. Re-running the job usually goes green, so it is a flake, not a deterministic failure.

Exact signature

Segmentation fault (core dumped)
##[error]Process completed with exit code 139.

The crash consistently lands at the end of the mocha run that contains the schema-change / index-rebuild tests (unitTests/resources/update-schema.test.js "Schema change", unitTests/resources/validation.test.js "Types Validation"), immediately after an index-rebuild state dump (indexingPID, lastIndexedKey: undefined, resolve: null) and two [main/0] [error]: Transaction was open too long and has been committed, from table: SchemaChanges/ warnings.

No native/JS stack is captured (no --report-on-fatalerror / abort handler), so only the OS-level segfault line is in the log.

Why it's a flake, not a code bug

Observed on plain main pushes (unrelated PR diffs). Passes on re-run with no code change. v24-only while v22/v26 are clean points to a Node v24 / native-addon (rocksdb-js / msgpackr) interaction during schema-change + background runIndexing, not a JS logic error.

Affected job / runtime

Unit Test (Node.js v24) only.

Evidence (all main, attempt 1)

• run 27718772847 / job 81998436331
• run 27718421204 / job 81997233958
• run 27696972188 / job 81922701975

Notes / next steps

• Add node --report-on-fatalerror (or --report-uncaught-exception) to the unit job so the next occurrence yields a native stack — currently we only get "Segmentation fault".
• Distinct from SIGSEGV crash in CursorWrap::close during rapid drop_table + drop_schema sequence #828 (CursorWrap::close on rapid drop_table+drop_schema), Worker SIGSEGV / heap corruption on records that fail to decode — native decode path is not fail-safe ([customer-cluster], 5.1.3/5.1.4) #1370 (decode-path heap corruption), and Re-enable LMDB caching tests #414 (LMDB caching tests) — different trigger (schema-change + reindex) and v24-specific.

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Filed by Claude (Opus 4.8) during CI flake triage while shepherding #1363/#1371/#1374.