zlacker

The main other problem is that the kernel doesn't register default signal handlers for signals like SIGTERM if the process is PID 1. So if your process doesn't register its own signal handlers, it's hard to kill (you have to use SIGKILL). I'm sure anyone who has used Docker a lot has run into containers that seem to just ignore signals -- this is the usual reason why.

> also, why can't the real pid1 do it? it sees all the processes after all.

How would the real PID 1 know if it _should_ reap the zombie? It's normal to have some zombie processes -- they're just processes whose exit statuses haven't been reaped yet. If you force-reaped a zombie you could break a program that just hasn't yet gotten around to checking the status of a subprocess it spawned.

>>dather+(OP)
Processes only reap their direct children. Init is special because orphaned processes are reparented to init, which then has to reap them.