$fp = fopen(sprintf("tmp/wk_exam_examination.%d.lock", $userid % 10), "w");
if (!flock($fp, LOCK_EX | LOCK_NB)) {
    ?>
  <style>
    #info {
      text-align: center;
      margin: 50px 0;
    }
    #info td {
      font-size: 36px;
      color: seagreen;
    }
  </style>
  <div id='info'></div>
  <script>
    let sec = 5000
    setTimeout(function () {
      window.location.reload()
    }, sec)
    setInterval(function () {
      sec -= 100
      if (sec >= 0) {
        let ok = sec / 1000
        document.getElementById('info').innerHTML = `<table style="margin: 0 auto;">
        <tr><td style='width: 50%; text-align: right;'>页面排队中...</td>
        <td style="width: 2em; text-align: center;">${ok}</td><td>秒后将重试！</td></tr></table>`;
      }
    }, 100)
  </script><?php
    die;
}