<"Fork fail!".PHP_EOL);
  } elseif ($pid == 0) {
    //获取信号量
    sem_acquire($signal);
    if (shm_has_var($shm_id,SHARE_KEY)) {
      $count = shm_get_var($shm_id, SHARE_KEY);
      $count++;
      //模拟业务处理
      $sec = rand(1, 3);
      sleep($sec);
      shm_put_var($shm_id, SHARE_KEY, $count);
    } else {
      $count = 0;
      $sec = rand(1, 3);
      sleep($sec);
      shm_put_var($shm_id, SHARE_KEY, $count);
    }

    echo "child process: ".getmypid()." is writing! now count is: $count ".PHP_EOL;

    //释放信号量
    sem_release($signal);
    exit("child process".getmypid()."end".PHP_EOL);
  } else {
    $child_list[] = $pid;
  }
}

while (count($child_list) > 0) {
  foreach ($child_list as $key => $pid) {
    $status = pcntl_waitpid($pid, $status);
    if ($status > 0 || $status == -1) {
      unset($child_list[$key]);
    }
  }
  sleep(1);
}

$count = shm_get_var($shm_id, SHARE_KEY);
echo " $count  ".PHP_EOL;

//销毁信号量
sem_remove($signal);

shm_remove($shm_id);
shm_detach($shm_id);