Found while chasing bug-1714's crash (root cause still open -- see that
entry): two related, independently-confirmed defects, not proven to be
bug-1714's own cause but real bugs on their own merits.
xce_core_push_events()'s JOBS_PUSH case never checked sched_add_job()'s
return value -- if key_add() failed (duplicate jobid), the freshly-built
xce_sched_job_t was handed to picker_iface->on_job_push() anyway, even
though it was never registered in core->jobs. An orphaned job the
picker knows about but sched_get_job() can never find again. Now checks
the return, frees the orphan (at core_build_job()'s own established
cleanup granularity -- xce_sched_job_t has no complete destructor
anywhere in this codebase, kill_sched_job() only frees ->rusages, so
this intentionally doesn't invent a more thorough one), and skips the
picker call.
This makes it safe to fix (not the other way around): sched_on_job_array()'s
per-element dedup check (handler.c) has a TOCTOU race -- a job is only
added to core->jobs later, by the driver thread, so a redelivered array
push arriving on the request thread before the driver catches up isn't
caught. Documented as a best-effort optimization, not a correctness
boundary -- the actual authoritative uniqueness check is sched_add_job()'s
key_add(), which the JOBS_PUSH fix above now handles correctly.
TDD: new test reproduces the duplicate-jobid path (RED: on_job_push
fired twice, Expected 1 Was 2), GREEN after the fix. Full scheduler
regression: 54/55, only the known bug-1561-adjacent flake.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019QxaSzHRB7pmYFp4cVnwkA
Rongsong Shen
38437e570e