go-reaper

Process (grim) reaper library for golang - this is useful for cleaning up zombie processes inside docker containers (which do not have an init process running as pid 1).

tl;dr

   import reaper "github.com/ramr/go-reaper"

   func main() {
	//  Start background reaping of orphaned child processes.
	go reaper.Reap()

	//  Rest of your code ...
   }

How and Why

If you run a container without an init process (pid 1) which would normally reap zombie processes, you could well end up with a lot of zombie processes and eventually exhaust the max process limit on your system.

If you have a golang program that runs as pid 1, then this library allows the golang program to setup a background signal handling mechanism to handle the death of those orphaned children and not create a load of zombies inside the pid namespace your container runs in.

Usage:

For basic usage, see the tl;dr section above. This should be the most commonly used route you'd need to take.

But for those that prefer to go down "the road less traveled", you can control whether to disable pid 1 checks and/or control the options passed to the wait4 (or waitpid) system call by passing configuration to the reaper.

import reaper "github.com/ramr/go-reaper"

func main() {
	config := reaper.Config{
		Pid:              0,
		Options:          0,
		DisablePid1Check: false,
	}

	//  Start background reaping of orphaned child processes.
	go reaper.Start(config)

	//  Rest of your code ...
}

The Pid and Options fields in the configuration are the pid and options passed to the linux wait4 system call.

See the man pages for the wait4 or waitpid system call for details.

   https://linux.die.net/man/2/wait4
   https://linux.die.net/man/2/waitpid