code: function reap()
      {
          for ($i = 0; $i < 100; $i++) {
              $pid = pcntl_waitpid(-1, $status, WNOHANG);
              if (-1 == $pid) {
                  break;
              } else if ($pid > 0) {
                  $this->logger->debug("did reape process {$pid}");
                  $this->removeWorkerById($pid);
                  continue;
              }
              $this->logger->debug("waitpid return pid is 0");
              break;
          }
      }
docs: REAP进程防治产生僵尸进程
  
  @return void