How to kill child processes that spawn their own child processes in Node.js

If a child process in Node.js spawn their own child processes, kill() method will not kill the child process’s own child processes. For example, if I start a process that starts it’s own child processes via child_process module, killing that child process will not make my program to quit.

var spawn = require('child_process').spawn;

var child = spawn('my-command');

child.kill();

The program above will not quit if my-command spins up some more processes.

PID range hack

We can start child processes with {detached: true} option so those processes will not be attached to main process but they will go to a new group of processes. Then using process.kill(-pid) method on main process we can kill all processes that are in the same group of a child process with the same pid group. In my case, I only have one processes in this group.

var spawn = require('child_process').spawn;

var child = spawn('my-command', {detached: true});

process.kill(-child.pid);

Please note - before pid. This converts a pid to a group of pids for process kill() method.