`ps | grep '/usr/bin/tachyon'` matches the hook itself, because
/usr/bin/tachyon is what invoked it. The sweep therefore killed its own
parent, the parent died on SIGKILL, and apk saw
`tachyon-<version>.pre-upgrade: exited with error 247` (128+119) and
reported a failed hook.
The sweep now walks /proc/<pid>/stat to collect its own ancestor chain and
skips those pids.
Holders of procd's serialization lock are also cleared by descriptor rather
than by name. procd_lock() does `exec 1000>` on
/var/lock/procd_tachyon.lock and then `flock 1000` with no -w, so any
background spawn inheriting fd 1000 keeps the lock held. On a live router
the holders were watchdog workers, logread, the zapret2 supervisors, nfqws2
and a stray curl — none of which match a tachyon name pattern. While any of
them lives, every init.d call blocks in flock until the package manager
gives up on the hook.
Same descriptor-based sweep added to install.sh, which faces the same lock
left behind by pre-fix builds.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
