Ruby recursive Process.kill

process_kill_recursive.rb

module Process::KillRecursive
  refine Process.singleton_class do
    def children(pid)
      pids = nil
      if RbConfig::CONFIG['host_os'] =~ /linux/i
        if File.exist?("/proc/#{pid}/task/#{pid}/children")
          pids = File.read("/proc/#{pid}/task/#{pid}/children").split(/\s/)
        end
      elsif !Gem.win_platform?
        pids = `ps --ppid #{pid} -o pid=`.split("\n")
        raise NotImplementedError unless $?.success?
      else
        raise NotImplementedError
      end
      pids.tap{|ps| ps.map!{|p| p.strip.to_i }.uniq! }
    end

    def kill_recursive(pid)
      # SIGSTOPs the process to avoid it creating new children
      begin
        Process.kill('STOP', pid)
      rescue Errno::ESRCH # The process was already killed
        return
      end

      # Gather the list of children before killing the parent (after the kill
      # children are re-attached to init and impossible to find)
      children = children(pid)

      # TODO: check if this do not generate <defunct> children
      # if it does, kill the process before it's children
      children.each do |cpid|
        kill_recursive(cpid)
      end if children

      begin
        Process.kill('KILL', pid)
      rescue Errno::ESRCH # The process was already killed
        return
      end
    end
  end
end

=begin
class SomeClass
  using Process::KillRecursive

  def some_method(pid)
    Process.kill_recursive(pid)
  end
end
=end