code: function manageWorkers()
      {
          $this->logger->debug("manage workers");
          $workers = $this->workers;
          while ($this->processes < count($workers)) {
              $worker = array_shift($workers);
              $this->logger->debug("kill {$worker->id()}");
              $this->kill($worker->id(), SIGQUIT);
          }
      }
docs: 杀掉多余的进程
  
  @return void