So on *nix systems PID 1 is supposed to be the init process. Any processes that lose their parent are *supposed* to be adopted by the init process so it can reap them.
You find out a lot about this when dealing with Docker containers and java processes. If your java process is PID 1 in the container, you’re going to be in for a bad time... Java process runs out of heap and spins in GC... so no signals handled correctly... cannot kill container... restart Docker Java process forks a shell script every 1s but doesn’t reap the dead processes forked by the shell script... your container will run out of handles... cannot kill container... restart Docker This is why a lot of people will use a minimal init process in Docker containers, eg tini (but there are others) Now if we have someone running a Maven build inside a Docker image (really nice with multistage Dockerfiles and COPY —from) and they do not understand (or agree with) the need for a minimal init then the assumption that all child processes will be reparented to PID 1 would be invalid. Similarly if a child handles reparenting of its grandchildren when the child dies then the PPID will stop there and not get to PID 1 until the owner dies *and nobody else* steps up to adopt Windows is a different case... no clue what goes on there On Fri 23 Feb 2018 at 19:06, Tibor Digana <tibordig...@apache.org> wrote: > Hi Michael, > > I found in C libraries documentation that PPID is =1 if the parent process > has exited - called native exit(). > Would the child process see PPID=1 in other cases too, like parent abort() > or segmentation fault? Can I rely on this on all platforms? > It might be easy detection of parent process has finished. > > Thx > Tibor > -- Sent from my phone
