Double-forks pve_mod_worker so it is reparented to init instead of the calling process, which reaps it immediately on exit and prevents it lingering as a <defunct> zombie. Also adds startup-time reaping of orphaned collector-* processes (ppid==1) left behind if a worker was previously killed with SIGKILL, and an opportunistic waitpid(WNOHANG) in _worker_lock_file_exists as a cheap supplemental reap.
Meliox