lei.chen/myxce
1
0
Fork 1
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
myxce/.wolf/bugs/bug-1881.md
Rongsong Shen 674b29c951
chore(gitea-sync): record Gitea sync state for 4 specs and bug-1878..1882 
Specs: scheduler-allocator-runner (#67: 317-319), scheduler-sim-decision-trace
(#68: 320, 324, 325), job-status-detail-display (#69: 321-323),
scheduler-sim-discrete-clock (#70: 326-328). Bugs: #329-#333.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-29 08:01:05 +00:00

4.5 KiB
Raw Blame History

id status status_updated status_note component severity timestamp last_seen occurrences files tags related fix_commits gitea_issue gitea_synced_status gitea_synced_hash
bug-1881 fixed 2026-09-29 scheduler wrong-result 2026-09-28T07:26:09Z 2026-09-28T07:26:09Z 1
src/scheduler/src/sim_verify.c
scheduler
sim
sim-verify
logging
24b05718
c1960457
2d7ba660
4e57bde6
332 fixed e7258ca9149c

bug-1881: sim_log_mismatch prints identical expected/actual, hiding the field that differs

Description

Observed:

... MISMATCH ... -- expected: DISPATCH jobid=0-12-1790578108-0[49] nhosts=1 -- actual: DISPATCH jobid=0-12-1790578108-0[49] nhosts=1

Expected: the message names the field(s) that differ, with both values. Impact: a mismatch cannot be diagnosed from the log (bug-1880: 43 such lines, none showing the difference). Found by: user reading the bug-1880 replay log, 2026-09-28

UPDATE (2026-09-28): Fix planned in spec libxce-alloc-preason-equality (Requirement 3, Requirement 5.3, task 5): the libxce equality functions gain an optional why/whylen buffer describing the first difference, and sim_log_mismatch appends it to the MISMATCH line.

Environment

  • OS: NixOS 26.05 (Yarara); NixOS kernel; kernel Linux 6.18.33 x86_64
  • libc: glibc 2.42-47 (interpreter /nix/store/wb6rhpznjfczwlwx23zmdrrw74bayxw4-glibc-2.42-47/lib/ld-linux-x86-64.so.2)
  • Toolchain: gcc (GCC) 15.2.0, meson 1.9.1
  • Build: debug (build.dbg)
  • Code: scheduler-framework @ 4c134127 (xce_scheduler --version: v0.0.0.1-4c134127-85e8fc00, built 2026-09-28T06:40:21Z)
  • Deployment: pc13v: xce_scheduler in simulation mode (pid 93231) replaying a capture of the live pc13v cluster's scheduler (scheduler-replay-20260928-064842.replay, captured from 06:48:42); exact command line and --sim-start-ts not recorded

Reproduction

  1. Any --sim-verify mismatch whose decisions differ only below the jobid/nhosts level (bug-1880's replay)
  • Frequency: deterministic (43/43 lines in the pc13v run)
  • Evidence: data/xce_scheduler.log

Root cause

sim_log_mismatch() (src/scheduler/src/sim_verify.c) summarizes each decision as kind + jobid + nhosts, while sim_decision_eq() also compares every host's allocations (resname, value, duration, reserve), so a difference there prints two identical summaries.

Fix

Spec libxce-alloc-preason-equality (commits 8f25c1c3..dcf3acf3). sim_decision_eq() now compares DISPATCH decisions with libxce's public job_alloc_eq() and returns a caller-owned first-difference description (char** why) naming the field path and both values; sim_log_mismatch() appends it as -- diff: <why>, and the replay loop in sim_loop.c passes and frees it (fixed text "no live decision" for leftover recorded decisions) — 24b05718. job_alloc_eq() also compares from, so the scheduler now stamps every allocation's from with the deciding session's start (scheduler.c sched_make_primary_alloc_, c1960457) and the normal-mode recorder takes beginRound from the same reading (driver.c, 2d7ba660), making from reproducible on replay.

The remaining gap (the simulator's own session-begin clock read drifting at --sim-speed >= 1) was closed by spec scheduler-sim-discrete-clock (4f653d8f..d9bc36cd: the simulator clock is pinned to recorded timestamps, --sim-speed is a no-op), so a replayed session starts at exactly the recorded beginRound and every replayed from matches; task 5.3 adds the proof (4e57bde6).

Verification

  • Test: test_log_mismatch_appends_provided_description and test_verify_against_altered_copy_reports_exact_mismatch (asserts -- diff: main_reason: 99 != 0) plus test_verify_leftover_recorded_decision_names_missing_side in src/scheduler/testsuite/test_sim_verify.c: RED before 24b05718 (no diff text on the MISMATCH line), GREEN after. test_sim_replay_reproduces_recorded_alloc_from in src/scheduler/testsuite/test_sim_live_allocation.c (4e57bde6): GREEN at default settings; a +0.5 s clock mutant at sim_loop.c's sim_advance_virtual_clock(sim, begin_round) makes it FAIL
  • Suites: ASAN debug build (src/xce.build.discrete), meson test --no-suite xceadmin: 117/117 OK, 0 Unity :FAIL lines, 0 sanitizer reports (2026-09-29)
  • Live: 2-round sequential HA soak (/home/claude/tmp/xce-alloceq-53, PASS, zero job loss) recorded 3 clean .replay files with 11 DISPATCH decisions; each replayed with xce_scheduler --sim --sim-verify and no --sim-speed (ASAN_OPTIONS=detect_leaks=0): rc=0, 0 MISMATCH lines

References

  • Related: bug-1880