class Rake::ThreadPool

def stat(event, data=nil) # :nodoc:
  return if @history_start_time.nil?
  info = {
    event: event,
    data: data,
    time: (Time.now-@history_start_time),
    thread: Thread.current.object_id,
  }
  @history_mon.synchronize { @history << info }
end