René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"gap CLI heap still grows during a klona run after #61 (87 to 821 MB after GC; unattributed)","articleBody":"## Summary\n\nOn the klona four-file suite (295 mutants, 2 contexts, seed 20261112), the gap CLI's child heap still grows during a run, after the retention fixes in #61. Heap after a forced GC, sampled every 2 s in the check child, went from about 87 MB at the start to about 217 MB in the middle and about 821 MB near the end. The run passes at a 1024 MB cap (child peak 930 MB) and completes at 1536 MB (child peak 985 MB). Main (before #61) fails at 2048 MB with a heap-limit fatal.\n\nThe growth is not attributed. The retention counters that #61 checks (Vitest's `filesMap`, `pathsSet`, `idMap`, the Vite copy nodes, the cold store, the stale context totals) stay at zero after each batch, so the remaining growth is in something those counters do not measure.\n\n## Measurement\n\nCommit: `2b7efe6` on `fix/gap-cli-retention` (#61). Probe: the heap sampler preload (`--expose-gc`, forced GC every 2 s, main thread of the check child only).\n\n```sh\n# heap after GC, first / middle / last samples\ncd \u003ccheckout of 2b7efe6>/packages/oracles/oracle-gaps\nSAMPLE_FILE=/tmp/heap.jsonl node --expose-gc --import ./probe-gc.mjs ./index.mjs \\\n  --package \u003cklona> --source src/index.js,src/lite.js,src/full.js,src/json.js \\\n  --seed 20261112 --contexts 2 --mutants \u003cmutants dir> --out \u003cout>\n\n# child peak heap, no probe, cap at 1024 and 1536 MB\nnode --max-old-space-size=1024 --import ./peak.mjs ./index.mjs \u003csame args>\nnode --max-old-space-size=1536 --import ./peak.mjs ./index.mjs \u003csame args>\n```\n\n`probe-gc.mjs` samples `process.memoryUsage().heapUsed` after `globalThis.gc()` every 2 s, in the child only (`ORACLE_GAPS_GROUP` set). `peak.mjs` samples `v8.getHeapStatistics().used_heap_size` every 250 ms and prints the peak at exit.\n\nNumbers, from the local runs against `67f057d`/`59363c8` code:\n- heap after GC: 87 MB (first sample), 217 MB (middle), 821 MB (last sample before exit);\n- 1024 MB cap: exit 0, child peak 930 MB;\n- 1536 MB cap: exit 0, child peak 985 MB;\n- default 2048 MB heap on `main` (affeb1a): heap-limit fatal, `done error ... ran out of memory`.\n\n## What is ruled out\n\n- Vitest state entries of retired copies (`filesMap`, `pathsSet`, `idMap`): 0 after each batch.\n- Vite module nodes of retired copies: 0 after each batch.\n- Vite nodes of non-copy files: at most one per file (the query-stripped check in #61).\n- The cold run's store (`memoryStore`): keeps nothing.\n- Vite's transform text, measured as a size on `ce6c93d`: flat.\n\n## What is not known\n\n- Which structure holds the second-half growth (from 217 to 821 MB). A late heap snapshot, taken near 700 MB, is the next step; its retainer path is not yet checked.\n- Whether the growth follows klona's per-file working set (later files have more mutants and larger tests) rather than residue.\n\n## Limits\n\nThis issue is about measured heap growth, not a claimed leak. The measurements are from one suite on one machine, under varying load.\n","author":{"url":"https://github.com/KyleAMathews","@type":"Person","name":"KyleAMathews"},"datePublished":"2026-11-14T17:07:00Z","url":"https://github.com/TanStack/oracles/issues/80"}