NodeJS child process experiments

• spawning child (and sub) processes
• blocking processes (stream + timers)
• sending signals

Keeping process open:

• pipes for stdin/stdout+stderr are established between the parent Node.js process and the spawned child
• holding process/shell open:
  • timers + stream (of data, via TCP sockets) hold it
  • spawn(process.execPath, args) -> holds (stream)
  • process.stdout.on('data') -> holds (stream)
    • same applies to parent or child process
  • setTimeout(() => { /* code */ }, 1000) - holds (timer)
  • process.on('SIGINT') -> doesnt hold (not a stream, an event)
• WHY:
  • child process waits to read all of its input
  • the child will not continue until the stream has been closed via end() or kill().
  • process.stdin.end() OR process.kill('SIGINT')
  • can pass kill event down stack i.e. parent -> child -> baby
• 'EXIT' event - emitted after the child process ends
  • IF nothing holding process will always run at end of script
  • ELSE signal could manually have exited it, will have signal.