Read an print zombie child process info in Ruby

testing_child_processes.rb

class ChildProcess
  class Ps
    attr_accessor :pid, :ppid, :state, :command

    def to_s
      "pid: '#{pid}', ppid: '#{ppid}', state: '#{state}', command: '#{command}'"
    end
  end

  attr_reader :list

  def initialize(ppid)
    @list = child_process_list(ppid)
  end

  def zombie_process
    @list.select { |child_process| child_process.state =~ /Z/ }
  end

  def zombie_process?
    @list.zombie_process(childs_process_list).any?
  end

  private

  def child_process_list(ppid)
    childs_process_list = []
    ps_pipe = `ps -o pid=,ppid=,state=,args= | grep #{ppid}`

    ps_pipe.split(/\n/).map do |line|
      ps_part = line.split(/\s+/)

      next unless ps_part[1].to_i == ppid

      child_process = Ps.new
      child_process.pid = ps_part[0]
      child_process.ppid = ps_part[1]
      child_process.state = ps_part[2]
      child_process.command = ps_part[3..-1].join(' ')

      childs_process_list << child_process
    end
    childs_process_list
  end
end


pid = Process.pid

puts "Current process pid : #{pid}"

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

10.times do
  puts ChildProcess.new(pid).zombie_process
  sleep 1
  puts '----'
end

puts Process.waitall

puts "Done"