Rongsong Shen
d26ff8870d
The buglog was one 27K-line JSON file whose fields covered only symptom,
root cause and fix, as free text: 2% of entries named the code version a
bug was found on, 12% the build profile, 36% a way to reproduce, and 58% of
the file was OpenWolf hook auto-detections ("Missing guard clause",
"Function not marked async" on .md files).
- .claude/skills/buglog/bug-record.md: the record standard. Eight
sections (Summary as the title, Description, Environment, Reproduction;
Root cause, Fix, Verification, References once fixed), each with the
content it must contain -- e.g. Environment needs the OS, the libc the
failing binary loads (from its ELF interpreter: glibc 2.42 in the nix
shell vs 2.40 on the host), toolchain, build profile and commit.
- .wolf/bugs/<id>.md: 500 records migrated from buglog.json; every field
verified to round-trip. They carry legacy: true and an explicit "not
recorded" where the old log had no such field; component derived from
file paths, severity from keywords (else unknown), fix_commits from
hashes in status_note/fix that git resolves (91 of 463 fixed).
- .wolf/buglog-archive.json: the 710 hook auto-detections, verbatim.
- .wolf/buglog.json is now an index generated from the records, keeping
the fields OpenWolf's hooks and `openwolf bug search` read.
- scripts/buglog.py rewritten: new (template + Environment collected from
the machine and --binary), check, status (refuses a status the record
doesn't support; fixed needs Root cause, Fix, Verification and
--commit hashes git resolves), note, recur, set, show, list, triage,
env, index. 29 unittest cases in scripts/tests/test_buglog.py.
- scripts/git-hooks/pre-commit runs `check --staged`: incomplete staged
records, a legacy record hand-changed to fixed without the fix-time
sections, a new record claiming legacy: true, or a stale index refuse
the commit.
- scripts/gitea-sync.py reads the records: issue body = the record's
sections plus linked fix commits (origin remote, GITEA_COMMIT_REPO to
override), and a body hash so an issue's text is refreshed when the
record changes.
- bug-1866 rewritten to the full standard as the worked example.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
41 lines
4.9 KiB
Markdown
41 lines
4.9 KiB
Markdown
---
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id: "bug-1842"
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status: "fixed"
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status_updated: "2026-09-24"
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status_note: ""
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component: "scheduler"
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severity: "unknown"
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timestamp: "2026-09-22T19:35:00Z"
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last_seen: "2026-09-22T19:35:00Z"
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occurrences: 1
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files: ["src/scheduler/src/sim_verify.c (sim_verify_alloc_eq", "the fix)", "src/lib/xcealloc.c (make_alloc", "the field's origin)", "src/scheduler/testsuite/test_sim_verify.c (new regression test)", "src/scheduler/testsuite/test_sim_live_allocation.c (stale-comment cleanup)"]
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tags: ["scheduler", "sim", "sim-verify", "replay", "from-field", "wall-clock", "make_alloc", "xcealloc", "decision-verification", "false-positive", "user-reported", "tdd"]
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related: ["bug-1611", "bug-1613", "bug-1779", "bug-1759", "bug-1838"]
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legacy: true
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gitea_issue: 77
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gitea_synced_status: "fixed"
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---
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# bug-1842: User-reported: replaying a real captured .replay file (scheduler-replay-20260922-095207.replay)…
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## Description
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User-reported: replaying a real captured .replay file (scheduler-replay-20260922-095207.replay) via --sim --sim-verify logged a MISMATCH for every single DISPATCH decision, even though the printed 'expected:'/'actual:' summaries (jobid, nhosts) were byte-for-byte identical on both sides -- e.g. 'expected: DISPATCH jobid=0-13-1790071174-0[44] nhosts=1 -- actual: DISPATCH jobid=0-13-1790071174-0[44] nhosts=1' still reported as MISMATCH. User asked whether the comparison should stop using a timestamp as part of its check condition.
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## Environment
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_Not recorded (migrated from buglog.json)._
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## Reproduction
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_Not recorded (migrated from buglog.json)._
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## Root cause
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sim_decision_eq()/sim_log_mismatch() (sim_verify.c) never compare the decision's own `ts` field (only log it for diagnostics) -- the user's timestamp hypothesis was right in spirit but aimed at the wrong field. The REAL culprit is buried one level deeper: sim_verify_alloc_eq() compares xce_alloc_t field-by-field including `from`, and make_alloc() (xcealloc.c:30) unconditionally stamps `alloc->from = time(NULL)` -- the real OS wall clock, not core.c's virtualized sim clock -- every time an allocation is built. `expected->from` (decoded from the .replay file) is whatever real second the ORIGINAL recording ran in; `actual->from` (freshly rebuilt by the live seqjob_allocator.c/parjob_allocator.c -> sched_make_allocs() -> make_alloc() chain during THIS replay) is whatever real second THIS replay runs in. Two independent real-world timestamps that essentially never coincide for any replay of a real recording, even though the decision itself (job/host/resource/value/duration) is exactly what was recorded. Confirmed empirically: a clean run of xce_scheduler --sim --sim-verify against the user's own replay file mismatched 120/120 DISPATCH decisions, 100% on this field, zero relation to real-time-vs-batch simulation speed (reproduced identically at --sim-speed=0, 1, and 20). The codebase already had a documented workaround for the same footgun elsewhere: dup_alloc() (xcealloc.c:179) has to re-stamp ->from/->duration from its source AFTER calling make_alloc(), specifically because make_alloc() clobbers them with the current wall time otherwise. A prior session (2026-09-21, see this same discovery independently reached and left unfixed) had already isolated this exact mechanism via test_sim_verify_no_false_mismatch_after_live_dispatch_and_later_confirmation's own header comment, which explicitly (and accurately, until this fix) documented it as accepted 'practically negligible' same-second-window flakiness.
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## Fix
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FIXED (2026-09-22). Dropped the `a->from == b->from` clause from sim_verify_alloc_eq() (sim_verify.c) with a doc comment explaining why: `from` is reservation-start bookkeeping (real wall-clock, for expiry/accounting purposes), not part of a DISPATCH decision's semantic identity -- unlike `duration`, which is a genuine request-derived value and stays part of the comparison. TDD: new test test_dispatch_decisions_differing_from_timestamp_still_match (test_sim_verify.c) builds two structurally-identical dispatch allocations with deliberately far-apart `from` values (1790000000 vs 1) and asserts sim_decision_eq() still reports a match. Also updated test_sim_live_allocation.c's test_sim_verify_no_false_mismatch_after_live_dispatch_and_later_confirmation header comment, which previously described this as accepted same-second-window flakiness -- now accurately states the flakiness is eliminated by construction. Full scheduler suite: 85/85 Ok, zero regressions (xce-build.sh scheduler asan --incremental). Live-verified against the user's own real replay file: DISPATCH-vs-DISPATCH false mismatches dropped from 120/120 to 0/120 (--sim-speed=0, --sim-verify, --logfile capture, before/after diff). A separate, distinct issue remains in the same file (61 'expected: <none> -- actual: PEND ... main_reason=0' mismatches) -- see bug-1843, not touched by this fix.
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## Verification
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_Not recorded (migrated from buglog.json)._
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## References
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- Related: bug-1611, bug-1613, bug-1779, bug-1759, bug-1838
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- Gitea: #77
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