Playing with child process in Ruby

childprocess.rb

pid = Process.pid

puts "Current process pid : #{pid}"

child_pids = []
6.times.each do |i|
  child_pids << Process.fork do
    Process.setproctitle("ruby childp n #{i} with #{i * 3}s")
    puts "sleeping #{i * 3}s"; sleep i * 3
  end
end

p Process.waitall

puts "Done"

Will print with while true; do pstree -s ruby; sleep 0.5; clear; done

       \-+= 71447 bti ruby grabbing_pid.rb
         |--- 71556 bti ruby childp n 1 with 3s
         |--- 71557 bti ruby childp n 2 with 6s
         |--- 71558 bti ruby childp n 3 with 9s
         |--- 71559 bti ruby childp n 4 with 12s
         \--- 71560 bti ruby childp n 5 with 15s