fix(wake): close fd 9 in the detector's sleep child so a dead detector's lock dies with it #993

Merged
Mos merged 4 commits from fix/966-detector-lock-fd-leak into main 2026-07-31 13:48:34 +00:00
@@ -529,7 +529,19 @@ cmd_run() {
echo "detector.sh: WARN — off-host liveness beacon emit failed (see beacon.sh); the off-host absence check remains the authoritative dead-man." >&2
fi
[ "$once" -eq 1 ] && break
sleep "$interval"
# Close the detector lock fd in the sleep child; otherwise an orphaned sleep
# keeps the single-instance flock (fd 9, taken at exec 9> above) alive after
# the detector parent dies. The lock is non-blocking (`flock -n`, above), so
# for as long as that sleep survives a replacement instance is REFUSED and
# exits rather than queueing. This particular hold is BOUNDED by one poll
# interval (WAKE_DETECTOR_INTERVAL, default 30s): when the orphaned sleep
# exits its copy of fd 9 closes, ending this bounded sleep-child hold. It
# does NOT follow that the next start succeeds — other inheritors of fd 9
# (the M1 adapter, M2 sink grandchildren) are outside this patch's scope and
# can keep holding the flock. The cost this removes is a restart window in
# which every supervisor retry fails on the sleep child's account.
# `9>&-` closes ONLY the child's copy — the parent's lock is unaffected.
sleep "$interval" 9>&-
done
}